LIBRARY OF CONGRESS. 

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UNITED STATES OF AMERICA. 



BRIEF LESSONS 



OK 



THE HUMAN BODY. 



AN ELEMENTARY TEXT-BOOK ON ANATOMY, PHYSIOLOGY, 
HYGIENE, AND THE EFFECTS OF STIMULANTS 
AND NARCOTICS ON THE HUMAN SYSTEM, 
PREPARED FOR THE USE OF INTER- 
MEDIATE AND GRAMMAR 
SCHOOLS. 



BY 

LAMONT STILWELL. 




NEW YORK: 
W. D. KERR, PUBLISHER, 

16 Astor Place 
1889. 



Copyright, 1889, 
By W. D. KERR. 



Press of J. J, Little & Co., 
Astor Place, New York. 



PREFACE 



This book is the result of several years' practical work in 
the class-room. It has been the practice of the author to 
teach the subject of Physiology topically, objectively, and 
with such simple experiments as can be performed with 
inexpensive apparatus. The notes prepared for the use of 
pupils have been revised and extended from time to time, 
until they have grown into the substance of this little book. 

In its preparation a logical order has been observed in 
the arrangement of subjects and in the sequence of topics, 
so that each lesson may be presented to the class orally and 
objectively before being assigned from the text. The sub- 
ject of each topic has been placed in the form of a question. 
Each question is a useful and interesting question, and 
deals with some important fact in regard to the structure 
or function of some of the organs of the body. 

In answering these questions it has been assumed that 
every teacher who uses this book will supplement each 
lesson with interesting conversation, and, as far as possible, 
with object-teaching and experiments. Consequently all 
matter which should be introduced orally by the teacher, or 
which should be brought out by observation, questions or 
experiments before the class, has been purposely omitted. 
An effort has been made to have the answers clear and con- 



4 PREFACE. 

cise, within the understanding of children, and as free as 
possible from scientific terms. 

Special care has been taken to present the leading facts 
of Anatomy and Physiology in such a way as to show clearly 
the reasons why the health of the body requires us to follow 
or avoid certain courses of conduct. In this way the gen- 
eral laws of health will be fixed in the minds of pupils as 
guiding principles, from which they can draw their own 
conclusions regarding special cases. 

In preparing this work the author has examined a great 
many text-books and other authorities upon the subject, and 
has used what he considered the best material, wherever 
found. A list of the text-books consulted, with the names 
and addresses of the publishers, is given on the following 
page. L. S. 

East Orange, N. J. 
September 1, 1889. 



TEXT-BOOKS CONSULTED. 



Walker's Anatomy, Physiology and Hygiene ; published 
by Bacon & Allyn, Boston, Mass. Hitchcock's Anatomy 
and Physiology, and Smith's Elementary Physiology and 
Hygiene'; published by Ivison, Blakeman, Taylor & Co., 
New York. Cutter's Analytic Anatomy, Physiology and 
Hygiene; published by J. B. Lippincott & Co., Philadel- 
phia. The Human Body, by H. Newell Martin ; published 
by Henry Holt & Co., New York. Steele's Hygienic Phy- 
siology ; published by A. S. Barnes & Co., New York. 
Hutchinson's Physiology and Hygiene ; published by Clark 
& Maynard, New York. Dunglison's Physiology ; pub- 
lished by Porter & Coates, Philadelphia. Kellogg's First 
Lessons in Physiology and Hygiene ; published by Harper 
& Brothers, New York. Brands' Lessons on the Human 
Body ^published by Leach, She well & Sanborn, New York. 
Blaisdell's Young Folks' Physiology ; published by Cow- 
perthwait & Co., Philadelphia. Huxley and Youmans' 
Physiology and Hygiene ; published by D. Appleton & Co., 
New York. Stowell's Syllabus of Lectures ; published by 
C. W. Bardeen, Syracuse, N. Y. 



™ 



CONTENTS 



CHAPTER PAGE 

I. A Talk to Pupils about our Bodies and the Object of this 

Book 9 

II. A General View of the Parts and Organs of the Body .... 12 

III. The Bones, or the Framework of the Body 15 

IV. Classes of Bones — Bones of the Head and Trunk 21 

V. Bones of the Upper and Lower Extremities 24 

VI. Hygiene of the Bones and Teeth 27 

VII. Food and Drink 32 

VIII. Organs of Digestion 37 

IX. Organs of Digestion — Continued 43 

X. Hygiene of Organs of Digestion .... 47 

XI. The Blood and its Circulation J. 55 

XII. The Organs of Circulation 59 

XIII. Hygiene of Organs of Circulation 66 

XIV. Organs of Respiration 73 

XV. Respiration and Voice 77 

XVI. Hygiene of Respiration 81 

XVII. Organs of Motion— Muscles 86 

XVIII. Hygiene of Muscles 90 

XIX. The Nervous System 95 

XX. Hygiene of the Nervous System 100 

XXI. The Skin and Organs of Special Sense 105 

XXII. The Skin and Organs of Special Sense — Continued 108 

XXIII. Hygiene of the Skin and Organs of Special Sense 114 

XXIV. Stimulants and Narcotics 118 

XXV. Stimulants and Narcotics— Continued , 123 



CHAPTER I. 

A TALK TO PUPILS ABOUT OUR BODIES AND THE OBJECT 
OF THIS BOOK. 

The great world about us has in it many curious and 
interesting things. If we stop to look, we find them every- 
where. Many of them are so close to us, and have become 
so familiar, that unless w T e stop to study them, they fail to 
excite our wonder or admiration. Among plants, animals, 
or anything else in all nature, there is nothing more won- 
derful than our own bodies. No study is more pleasing, no 
knowledge is more valuable, than that so closely connected 
with ourselves. 

Boys and girls find themselves taller and larger this year 
than they were last! How did they become so ? " They 
grew." Yes, they ate and grew; but how did the food 
which they ate find its way to the very extremities of the 
body, and become flesh and bone ? As you have been out 
in the fields alone on a cold winter's day, did you never ask 
yourself why it was that while everything about you was 
cold, your body was warm ? Our homes, the horse-cars, 
and the schoolroom must have fires in them to keep them 
warm ; but w T hat is the source of the heat which keeps our 
bodies warm ? It would be of interest to know. Again, 
we notice that unless somebody moves them, the trees live 
and spend their lives in the places where they began to 
grow ; while we and other animals move about where we 



10 BRIEF LESSONS ON THE HUMAN BODY. 

will. Both, we say, are alive ; but how is it that we have 
a power which the tree has not ? A clock ticks, and its 
wheels move. I ask you why, and you say that it has a 
spring in it which, when wound up, gives to the wheels the 
power of motion. When it runs down the wheels stop, 
and somebody must wind it again. Our hands move, but 
they do not wait like the boughs of the tree for a breath 
of wind to stir them. Our bodies move, but they do not 
have to be wound up like the clock. Why is it ? Where 
do we get the power ? Why must we eat and drink ? 
Why must we breathe ? How do we see and hear ? Why 
must we sleep ? Why is it that improper food or exposure 
will make us sick ? By and by, on account of sickness, an 
accident, or old age, we become as cold and as motionless 
as the stones themselves. What has happened ? 

These are only a few of the great many interesting ques- 
tions which we can ask about our bodies. Some of them 
neither you, nor I, nor any one else, can answer fully ; but 
many of them can be answered, and perhaps all of them in 
part. 

To answer some of these questions is the object of this 
little book. We hope that some of the boys and girls who 
use it will become so much interested in this study that 
they will be eager to study other books and to make inves- 
tigations for themselves. Many things can be best learned 
by handling and examining them instead of reading about 
them. We cannot see how things are arranged, or what 
takes place within our own bodies ; but, if we will, we can 
find out much by carefully examining the dead bodies of 
animals. A dead rabbit, the heart of a sheep, or the bones 
of an ox,, will afford a more interesting lesson than any 
book. 



OUR BODIES AND THE OBJECT OF THIS BOOK. 11 

As we study, we shall find that in some respects our 
bodies are like houses ; they afford a home and protection 
to what is within them. In other respects they are like 
machines, each part of which has some particular work to 
do. If we wish to know all about a machine, a pump, a 
watch, or a sewing-machine, we study all its parts, how 
they are put together, and what each part does. In order 
that the machine shall work well and last long, we must 
know how to use it and how to take care of it. It is just 
so with the machine which we call our body. You know 
it sometimes gets out of order, and we say we are sick, and 
we send for the physician in order that he may advise us 
what to do to remove the difficulty, and to put the machine 
in good working order again. 

To avoid sickness and pain, and to prolong life and 
strength as long as possible, is a matter of great importance 
to each one of us. In order to do this, we must under- 
stand the human machine, our body. We must learn all 
its parts, know how they are put together, w T hat they are 
for, and how they work. We also must learn how to take 
care of the body, so that it will be strong and last as many 
years as possible, and give us the least amount of pain. 

Each part of the body which does some work is called 
an organ. The eye, the ear, the hands, the heart, the 
stomach, etc., are all organs. The study of the organs of 
the body, how they are made and put together, is called 
Anatomy. The study of the office of each one of these 
organs, or what it does, is called Physiology. The study by 
which we learn to take care of the organs of the body is 
called Hygiene. This book is intended to teach you some- 
thing of Anatomy, Physiology, and Hygiene. 



CHAPTEE II. 

A GENERAL VIEW OF THE PARTS AND ORGANS OF THE 

BODY. 

What are the principal parts of the body? 

The principal parts of the body are the trunk ; the head ; 
the upper extremities, or arms ; and the lower extremities, 
or legs. 

What are the chief parts of the trunk ? 

The chief parts of the trunk are the chest, the abdomen 
(ab-do'-men), and the backbone. 

What are the chief parts of the head? 

The chief parts of the head are the skull and face. The 
forehead, temples, cheeks, eyes, ears, nose, mouth, etc., may 
be called parts of the face. 

What are the chief parts of the upper extremities ? 

The chief parts of the upper extremities are in each arm 
a shoulder, an upper-arm, a fore-arm, a wrist, and a hand. 
The fingers are parts of the hand. 

What are the chief parts of the lower extremities ? 

The chief parts of the lower extremities are in each leg a 
hip, a thigh, a lower-leg, an ankle, and afoot. The toes are 
a part of the foot. 

With what is the entire body covered? 

The entire body is covered with the skin, to which 
belong the hair of the head, and the nails which grow at 
the ends of the fingers and toes. 



PARTS AKD ORGANS OF THE BODY. 13 

What is an organ of the body ? 

An organ is any part of the body which has some special 
work to do. 

Name the principal sets of organs in the body. 

The principal sets of organs are the bones, which give 
form and support to the body ; the organs by which we 
digest our food, called the organs of digestion ; the organs 
which pump and carry the blood through the body, called 
the organs of circulation ; the organs used in breathing 
and talking, called the organs of breathing ; the organs by 
which we know, see, hear, feel, etc., called the organs of 
the nervous system ; the organs which enable us to move 
any part of the body, called the muscles, or the organs of 
motion. 

What is the bony frameiuork of the body called ? 

The bony framework of the body is called the skeleton. 

What is the principal organ of digestion, and ivhere is it 
situated ? 

The principal organ of digestion is the stomach. It is 
situated in the upper part of the abdomen. 

What is the principal organ of circulation, and ivhere is 
it situated? 

The principal organ of circulation is the heart. It is 
situated in the central part of the chest. 

What are the principal organs of breathing, and where 
are they situated ? 

The principal organs of breathing are the lungs. They 
are situated in the chest, one on each side. 

What is the principal organ of the nervous system, and 
where is it situated? 

The principal organ of the nervous system is the brain. 
It is situated in the cavity of the skull. 



14 BRIEF LESSONS ON THE HUMAN BODY. 

What are the muscles, and where are they situated ? 

The muscles are the reddish flesh, or lean portions of the 
body. They are situated in all parts of the body. 

What are all the solid parts of the body called? 

All the solid parts of the body, such as bones, muscles, 
fat, etc., are called tissues. 



CHAPTER III. 

THE BO^ES, OR THE FRAMEWORK OF THE BODY. 

What are the uses of the bones ? 

The uses of the bones are, to protect the delicate organs 
which are enclosed by them ; to support the body and to 
give it form ; and to act as levers by which the muscles 
attached to them may move the body. 

Name some important organs which are protected by the 
bones. 

The brain is protected by the bones of the skull. The 
heart and lungs are protected by the bones which enclose 
the chest. The spinal cord is protected by the bones of the 
spinal column, or backbone. The eye is protected by the 
bones of the face. 

Wliat can be said about the form of the bones f 

The bones vary greatly in form. Some are long, some 
are short, some are flat, and others are irregular in 
form. 

Mention some bones of the body which may be called long 
bones. 

The bones of the upper-arm, fore-arm, thigh, andjower- 
leg, may be called long bones 

Mention some bones ivhich may be called short bones. 

Examples of short bones are found in the wrist, ankle, 
and spinal column. 

Mention some examples of flat bones. 



16 



BRIEF LESSONS ON THE HUMAN BODY. 




THE FRAMEWORK OF THE BODY. 

THE SKELETON. 



17 



The Head, 28 Bones. 



Occipital (base of skull) 
Parietal (sides of skull) 
Temporal (temples) . . 
Frontal (forehead) . . 
Sphenoid (behind the face) 
Ethmoid (behind the face) 
Nasal (bridge of nose) . 
Vomer (between nasal fossa?) 
Turbinated (on walls of nasal 
fossce) 



Palate (back part of roof of 

mouth) ....... 2 

Lachrymal (in orbit) ... 2 

Malar (cheek-bones) .... 2 

Superior Maxillary {upper 

jaw) 2 

Inferior Maxillary (loicer 

jaw) 1 

Malleus (in the ear) ~) ^_j ( 2 

Incus (in the ear) > & 3 ■< 2 

Stapes (in the ear) ) M ( 2 



Vertebrae 

Sacrum 

Coccyx 



The Trunk, 52 Bones. 

(backbone) 



. 24 
. 1 
. 1 



Hyoid (in the neck) .... 1 
Ribs 24 

SternUxM (breast-bone) . . ' . 1 



The Upper Limbs, 64 Bones. 



Scapula (shoulder-blade) . . 2 

Clavicle (collar-bone) ... 2 

Humerus (arm-bone) .... 2 

Radius (fore-arm) .... 2 



Ulna (fore-arm) . 
Carpus (wrist) . . 
Metacarpus (hand) 
Phalanges (fingers) 



2 

16 
10 

28 



The Lower Limbs, 62 Bones. 



Innominate (hip-bone) ... 2 

Femur (thigh-bone) .... 2 

Patella (knee-pan) .... 2 

Tibia (leg) 2 

2 



Fibula (leg) 2 

Tarsus (ankle, heel, instep) . 14 
Metatarsus (flat of foot) . . 10 
Phalanges (toes) . . . . . 28 



18 BRIEF LESSONS ON THE HUMAN BODY. 

Examples of flat bones are the bones of the skull, the 
ribs, the breast-bone, and the shoulder-blades. 

Why are some bones hollotv ? 

If the bones of the limbs were solid, they would have to 
be much heavier. Their hollow form gives them greater 
strength than the same amount of bone would have in a 
solid form. 

Describe the structure of a bone. 

The outside part of a bone is hard, but within it is some- 
what softer and hollow. The hollow portions are filled 
with a spongy substance called the marrow. 

Of ivhat materials are bones composed ? 

Bones are composed of animal matter, a jelly-like sub- 
stance, and of mineral matter, mostly lime. 

What is the use of the animal matter ? 

The use of the animal matter is to give toughness and 
elasticity to the bones. 

What is the use of the mineral matter ? 

The use of the mineral matter is to give hardness and 
stiffness to the bones. 

How do the bones of an infant differ from those of an old 
person ? 

The bones of an infant are merely cartilage ; they con- 
tain an abundance of animal matter, but less mineral mat- 
ter ; they are tough and not easily broken. The bones of 
an old person contain more mineral matter, which makes 
them hard and brittle, and more easily broken. 

How do bones groiv ? 

The materials of which bones are composed are contin- 
ually being worn out and replaced by new material. Bones 
grow, chiefly, by additions to their free ends and surfaces. 
The blood circulates freely through the bones, and supplies 



THE FRAMEWORK OF THE BODY. 19 

them with the materials which are required for their growth 
and nourishment. 

How is a broken bone repaired? 

The blood carries and leaves at the broken place a watery 
fluid which contains the materials of which gristle is formed. 
This hardens and cements the broken ends together until 
the blood in the same way gradually adds the mineral mat- 
ter and completes the union. 

How are the bones held together ? 

The bones are held together by strong bands of tissue, 
called ligaments. The muscles also help to hold them in 
place. 

What is a joint ? 

A joint is the place where two bones unite. 

How are joints classified ? 

Joints are classified as movable, immovable, and mixed. 

Give examples of each hind. 

The joints of the bones of the arms and legs are movable. 
The joints of the bones of the skull are immovable. The 
joints of the bones of the spinal column (backbone) are 
mixed. 

Hotv many hinds of movable joints are there ? 

There are three kinds of movable joints. They are 
called hinge joints, ball-and-socket joints, and irregular 
joints. 

Give examples of each kind. 

The joints of the elbows, knees, and fingers are hinge 
joints. The joints of the shoulders and hips are ball-and- 
socket joints. The joints of the w T rists, ankles and neck are 
irregular joints. 

How do these joints differ from each other ? 

The hinge joint permits motion in only two directions, as 



20 BRIEE LESSON'S ON THE HUMAN BODY. 

backward and forward, like the hinges of a door. The 
ball-and-socket joint allows motion in every direction, for- 
ward, backward, and in a circular manner ; it consists of a 
ball at the end of one bone, which fits into a socket in the 
end of another. The irregular joint is one in which the 
surface of one bone moves only a little on the surface of 
another ; such joints are useful where little motion but 
great strength is required. 

How does nature provide for the oiling of the joints ? 

In the cavity of each joint there is a thin lining, or mem- 
brane, which gives out a fluid called joint-water. This 
serves as oil to the joint. 



CHAPTER IV. 

CLASSES OF BOXES. — BONES OF THE HEAD AND TRUNK. 

How many bones in the human skeleton ? 

The number of bones in the human skeleton is 206. The 
number varies somewhat at different periods of life. That 
which is merely gristle, or cartilage, in infancy, becomes 
bone later in life. 

How may the bones of the skeleton be divided ? 

The bones of the skeleton may be divided into four 
classes, viz. : bones of the head, bones of the trunk, bones 
of the upper extremities, and bones of the lower extremities. 

Hoiv many bones in the head ? 

In the head there are twenty-eight bones. Eight of them 
form the skull, fourteen are in the face, and six in the ears. 
(For the names of the bones of the head see table on page 17.) 

Describe the construction of the skull. 

The bones of the skull form a cavity in which the brain 
is situated. These bones are united by peculiar notched 
joints, called sutures. The cavity has an opening at the 
bottom through which the spinal cord enters. There are 
no other openings except very small ones through which 
nerves and blood-vessels enter or pass out. The upper 
bones of the skull consist of two hard plates, with a spongy 
layer between them. 

Describe the uses of the bones of the head. 

The bones of the skull and face protect the brain and 



22 BRIEF LESSONS ON THE HUMAN BODY. 

the organs of sense— smell, taste, hearing, and sight — from 
injury. The bones of the ear are an aid in hearing. The 
jaws contain the teeth, and are used in masticating food. 

What is the only movable bone in the head ? 

The only movable bone in the head is the lower jaw. It 
can be moved in five different directions. Its joints are 
very liable to dislocation. 

How many teeth appear in infancy ? In later life ? 

The temporary, or milk teeth, which appear during 
infancy, are twenty in number, ten in each jaw. The per- 
manent teeth, which appear later, are thirty-two in number, 
sixteen in each jaw. 

What names are given to the permanent teeth, and hozv 
many of each hind ? 

The names and number of the permanent teeth on each 
jaw, beginning at the back part of the mouth, are : two 
wisdom, four molars, four bicuspids, two canine, and four 
incisors. 

Are the teeth regarded as bones ? Why ? 

The teeth are not regarded as bones. They differ from 
bones in several respects. They are covered with an enamel, 
which bones have not ; when broken a tooth decays, a bone 
will repair itself ; teeth differ from bones in manner and 
time of growth ; teeth do not appear in the infant at birth, 
bones do ; the first set of teeth drop out and are replaced 
by others, no such thing takes place with the bones. 

Hoiv many bones are found in the trunk ? 

In the trunk there are fifty-two bones. They are located 
as follows : in the spine, twenty-four bones ; ribs, twenty- 
four bones ; breast-bone, one ; sacrum, one ; coccyx, one ; 
at base of the tongue, one. (For the names of the bones of 
the trunk, see table, page 17.). 



BONES OF THE HEAD AND TRUNK. 23 

What cavities are formed by the bones of the trunk ? 

Two cavities are formed by the bones of the trunk. 
The upper one, called the chest, is enclosed by the spine, 
ribs, and sternum ; the lower one, called the abdomen, is 
enclosed by the spine at the back, the bones of the pelvis 
below, and by muscles in front. 

What organs are found in the chest? 

The lungs and heart are found in the chest. 

What organs are found in the abdomen ? 

The abdomen contains the stomach, intestines, liver, 
kidneys, and other organs. It is the largest cavity of the 
body. 

Describe the spinal column. 

The spinal column extends from the head to the bones of 
the pelvis. It consists of twenty-four bones so put together 
that the body can turn on them readily. These bones are 
called the vertebrce. Through the spinal column there 
extends a tube-like canal, called the spinal canal, which 
contains the spinal cord. 

What is the use of the spinal column ? 

The spinal column protects the spinal cord ; it holds the 
body in an upright position, yet allows it to bend when we 
will ; it supports the weight of the head, arms, chest, etc. 

Describe the ribs. 

The ribs are slender, curved bones, which help to enclose 
the cavity of the chest. They are arranged in pairs, twelve 
on each side. 

What is the Use of the ribs ? 

The use of the ribs is to afford protection to the lungs, 
heart, and great blood-vessels. They also furnish an 
attachment for the muscles which move the walls of the 
chest when we breathe. 



CHAPTER V. 

BONES OF THE UPPER AND LOWER EXTREMITIES. 

How many hones in the upper limbs, or arms ? 

In the upper limbs, or arms, there are sixty-four bones. 
(For their names see table, page 17.) 

Describe the scapula, or shoulder-blade. 

The scapula, or shoulder-blade, is a broad, thin, flat, 
triangular bone situated at the top and back of the chest. 
It is not directly attached to the trunk, but is held in place 
by muscles. It is connected with the collar-bone, and con- 
tains the socket of the shoulder-joint. 

What is the use of the scapula? 

The use of the scapula is to make an attachment for the 
muscles of the shoulder, and to connect the arm with the 
trunk of the body. 

Describe the clavicle, or collar-bone. 

The clavicle, or collar-bone, is a long, slender bone which 
extends from the breast-bone and first rib to the shoulder- 
blade. 

What is the use of the clavicle ? 

The use of the clavicle, or collar-bone, is to brace the 
shoulders back and to hold them out from the chest. 

Describe the bones of the arm. 

That part of the arm between the shoulder and elbow 
consists of a single bone, called the humerus. That part 
between the elbow and wrist consists of two bones, called 



BONES OF THE UPPER AND LOWER EXTREMITIES. 25 

the ulna and the radius. To these bones are attached a 
large number of muscles which move the hand and fingers. 
The radius is on the thumb side of the arm, the ulna is on 
the side of the little finger. 

What advantage comes from having two tones in the fore- 
arm? 

It permits an arrangement of joints which allows the 
fore-arm and hand to take a rolling motion which turns 
the palm of the hand up or down. 

Describe the wrist, or carpus. 

The wrist is situated between the fore-arm and the hand. 
It contains eight bones, irregular in shape, arranged in two 
rows. The bones are held together by strong ligaments, 
and form an irregular joint. 

Describe the bones of the hand. 

The bones of the palm of the hand are fi^e in number in 
each hand. They are joined at one end with the bones of 
the wrist, at the other with the bones of the fingers or the 
thumb. There are three bones in each finger, but only two 
in each thumb ; they are called the phalanges. 

Bow many bones in the lower extremities, or legs? 

In the lower extremities, or legs, there are sixty-two 
bones. (For the names of these bones, see table, page 17.) 

What is the pelvis, and what is its use? 

The pelvis is the bony structure at the base of the trunk. 
Its use is to make a foundation for the support of the spinal 
column and for the weight of the body above it. The hip- 
bones, which form a part of the pelvis, contain the sockets 
for the attachment of the thigh-bones, and thus connect the 
trunk of the body with the lower extremities. 

Describe the hip-joint. 

The hip-joint is a ball-and-socket joint. At the upper 



26 BRIEF LESSONS ON THE HUMAN BODY. 

end of the thigh-bone, or femur, there is a ball which fits 
snugly into a deep socket in the side of the pelvis. The 
hip-joint is similar to the shoulder-joint, and permits mo- 
tion in eyery direction. 

Describe the knee-joint. 

The knee-joint is a hinge joint. It is formed by the join- 
ing of the thigh-bone with one of the bones of the lower leg, 
the tibia. Over the joint in front is a little heart-shaped 
bone, called the knee-pan, or patella. It protects and 
strengthens the joint. 

Describe the bones of the lower leg. 

The lower leg has two bones, the tibia and fibula. The 
tibia is a strong bone. It has a sharp ridge in front, called 
the shin. The fibula is the outer bone of the lower leg. It 
is fastened at both ends to the tibia. It serves as a brace 
to the tibia, protects the ankle-joint, and affords an attach- 
ment for muscles. 

Describe the ankle. 

The joint at the ankle is similar to that of the wrist. The 
bones here are seven in number, and form the ankle, heel, 
and instep. 

Describe the bones of the foot. 

The bony structure of the foot is quite similar to that of 
the hand. Besides the seven bones of the ankle and instep, 
which have just been mentioned, there are in each foot 
nineteen other bones, — in the "flat "of the foot, five bones, 
called the metatarsals; in the toes, fourteen bones, called 
the phalanges, — making twenty-six bones in all. 



CHAPTER VI. 

HYGIENE OF THE BONES AND TEETH. 

From what sources does the body derive the materials for 
making bones % 

The materials for making bones are derived from the food 
we eat and the water we drink. 

In order that the bones may be strong and healthy, tohat 
must our food contain ? 

Our food must contain a proper amount of bone-making 
material, otherwise our bones will become weak and un- 
healthy. 

What disease of the bones is sometimes caused by ivant of 
proper food ? 

The disease called rickets is caused by a deficiency of 
mineral matter in the bones. The bones become soft, and 
are drawn out of shape by the muscles, producing de- 
formity. 

Mention some articles of food tvhich are rich in bone- 
making material: 

Milk, eggs, oatmeal, and bread made from coarse flour or 
whole grain, are foods which are rich in bone-making ma- 
terial. In making fine white flour the miller takes out the 
part that is most useful for making strong and healthy 
bones. 

Name some foods which are deficient in bone-making ma- 
terial. 



28 BRIEF LESSONS ON THE HUMAN BODY. 

Sugar, candy, fat meats, and bread and cakes made from 
fine flour, are deficient in bone-making material. 

What is the cause of " boiv-legs " in infants ? 

The bones of infants are soft and easily bent. If young 
children are allowed to stand on their feet too much, the 
weight of the body bends the legs outward. As the bones 
gradually harden they retain their curved shape and become 
permanently deformed. 

What effect has exercise upon the hones ? 

As is the case w 7 ith all other organs of the body, a proper 
amount of exercise helps to keep the bones in a strong and 
healthy condition. The exercise should not be too severe 
or too long continued. 

Wliat deformities are caused by improper positions in sit- 
ting, standing, or tvorking ? 

The bones of young persons, being soft and flexible, are 
easily bent out of shape by improper positions in sitting, 
standing, or working. In this way hollow chests, round 
shoulders, curved spines, and other deformities are formed. 

What injurious effects may come from tight clothing about 
the ivaist ? 

Serious distortion of the spine and bones of the chest may 
be caused by tight clothing about the waist. If worn by 
young people, the ribs are pressed inward so that they inter- 
fere with the proper action of the important organs situated 
in the cavity of the chest : the heart, lungs, stomach, and 
liver. Diseases of the liver, dyspepsia, and consumption 
are often the results. 

What is the disease called a ''felon " ? 

The disease called a felon is an inflammation that com- 
mences in or beneath the periosteum, a membrane which 
covers the bone. It is very painful. Relief is usually found 



HYGIENE OF THE BONES AND TEETH. 29 

by opening through the periosteum to the surface of the 
bone. The quicker the incision is made, the less risk and 
the less suffering. 

Why is it a bad practice for children to "crack" the 
knuckles by pulling the fingers ? 

The practice which children sometimes have of pulling 
the fingers so as to "crack" the knuckles is foolish and 
harmful. It weakens the joints, and causes them to grow 
large and unsightly. 

Is the use of alcohol and tobacco injurious to the bones? 

The use of alcohol and tobacco does not have so marked 
an effect upon the bones as upon some other organs. A 
man's height depends upon the length of his bones. The 
boy who smokes cigarettes, or who uses alcoholic liquors, 
is likely to be so stunted that even his bones will not grow 
to a proper length, and he will become dwarfed or deformed. 

Mention three things to be observed in the care of the 
teeth. 

The teeth should be kept clean : they should not be used 
to crush hard substances ; teeth which have begun to 
decay should be filled or removed. 

Why should the teeth be kept clean ? 

If particles of food are left between the teeth, on ac- 
count of the moisture and warmth of the mouth they begin 
to putrefy. This not only causes the teeth to decay, but 
makes the breath very offensive. 

How can the teeth best be kept clean f 

The teeth are usually best kept clean by the use of a 
soft tooth-brush and pure water thoroughly applied at least 
once in the twenty-four hours. A good tooth-powder can 
occasionally be used with benefit. A toothpick, made of 
wood, ivory, or quill, or of some other substance softer 



30 BRIEF LESSONS ON THE HUMAN BODY. 

than the tooth itself, should be used after each meal. A 
hard toothpick, like a pin or needle, is likely to scratch the 
enamel of the tooth, and thus cause it to decay. 

Wliy is it a bad practice to crack nuts with the teeth, 
or to bite other hard substances? 

The cracking of nuts, or even the constant biting of 
thread, or any hard substance, is injurious to the teeth 
because it is liable to break the hard enamel of the teeth 
and thus expose the inner and softer portions to the action 
of the air and the liquids of the mouth, causing decay. 

Why should decaying teeth be filled or removed? 

If the decay of a tooth is not stopped, it will soon begin 
to cause pain, and its service in preparing food will finally 
be lost. If taken in season and properly filled, its useful- 
ness may often be prolonged many years. Besides this, a 
decaying tooth is a filthy thing to have in the mouth. Its 
presence there taints the breath, and produces decay in 
others ; consequently, if a tooth is past filling, it should be 
removed at once. 

NOTES AND SUGGESTIONS. 

Note 1. Power of Bones to Resist Decay. — Bones and teeth have a 
remarkable power of resisting decay. They remain long after all other 
parts of the body have wasted away. Bones have been found which 
belonged to animals that lived before man appeared on the earth. The 
teeth resist decay even longer than the bones. 

2. Weight of Skeleton. — The weight of the skeleton is about one- 
tenth that of the entire body ; consequently, the weight of the bones of 
a man of 140 lbs. would be about 14 lbs. 

3. Strength of Bones. — The strength of human bones when used as 
levers, as compared with other substances, is remarkable. Bones con- 
taining the same amount of material are twice as strong as oak timber. 

4. Chemical Composition of Bone. — Of 100 parts of bone, 33 are 



NOTES AND SUGGESTIONS. 31 

organic substance or cartilage, 57 are phosphate of lime, 8 are carbon- 
ate of lime, and the other 2 are fluorid of calcium and phosphate of 
magnesia. 

5. Proof of Animal Matter. — Immerse a bone for a few days in 
dilute muriatic or sulphuric acid. The acid will eat out all the lime, 
or earthy matter, leaving the cartilage, which will be so soft and flexi- 
ble that it may be tied in a knot. The experiment can be easily tried 
with the bone of a chicken's leg. 

6. Proof of Mineral Matter. — Place a bone for a short time in a 
hot fire. All the animal matter will be burned out, leaving the lime, 
or mineral matter. This will be white and brittle, and easily crushed 
to a powder. 

7. Proof that the Blood Circulates through the Bones. — If madder 
be mixed with the food of an animal, the bones soon become red. 

8. Suggestions. — The fresh bones of the leg of a sheep or calf can 
readily be obtained from the market. Everything that can be learned 
objectively by examining the specimens should be learned before 
assigning a lesson from the text-book. The internal structure can be 
examined by sawing the bone longitudinally aud cross-wise. Have 
also before the class a dry bone, and let pupils note the differences 
between this and the fresh one. If possible, examine the structure 
of bone with a microscope. Glass slides containing specimens 
already prepared can be had for a few cents. If the school is not 
provided with a skeleton, the structure of the skull, joints, etc., can 
be understood by examining the skull of a rabbit or cat. It will be of 
interest to compare the human skeleton with that of other animals. 
Some animals have the skeleton outside; as, crabs, lobsters, oysters, 
clams, etc. The skeleton of the turtle is peculiar. The teeth of 
various animals may be compared. In doing so, note the relations 
between the form and structure of the teeth and the kind of food 
upon which the animal lives. 



CHAPTER VII. 

FOOD AND DKIKK. 

What is food? 

A food is any substance, solid or liquid, which, when 
taken into the body, repairs the waste or prevents the loss 
of any of its tissues. 

Why do ive need food ? 

We need food to repair the waste caused by the wearing 
out of tissues, to keep up the warmth of the body, and in 
growth to supply material for new tissues. 

What are the evidences that the tissues of the body waste, 
or tvear out ? 

If little or no food be taken for a time, the body, as we 
say, becomes thin and poor, and gradually loses in weight. 
If we are compelled to continue to do without food, the 
body continues to lose weight, until finally death ensues. 
Loss in weight simply means loss, or waste, of tissues. 

What are the causes of waste ? 

Motion everywhere is followed by waste. The stream 
w r ears away its banks ; the steam-engine uses up coal and 
water to produce motion, and is itself worn out by the 
motion produced. The burning of coal in producing heat 
is called chemical action; the w r ear caused by the motion 
of the machinery is due mostly to friction. So it is with 
our bodies : the motive-power is furnished by the food we 
eat ; but, unlike the engine, our food is not burned in a 



FOOD AND DRINK. 33 

separate part of the body. The food becomes a part of the 
body, and, therefore, it is the whole body that is slowly 
burning. Nevertheless w T e can say, as of the engine, that 
the causes of waste are chemical action and friction. 

Hoiv do we know that food keeps the body ivarm ? 

If we go out on a cold day without having eaten a suffi- 
cient amount of food, we feel chilly and cold, when with a 
hearty meal we would be comfortable and warm. We need 
more and heartier food in winter than in summer. Thus 
w r e all know that mother's advice on a cold day is correct, 
when she says, "Eat a hearty breakfast before you go out, 
or you will be cold." 

Why does a child need more tissue-making food than a 
grown person ? 

A grown person needs only the food necessary to renew 
worn-out tissues, while a child must have not only food 
enough to renew the worn-out tissues, but enough more 
to make the new tissues required for his growth. 

Why do ive need more than one kind of food ? 

In order to keep the body warm, and to provide for the 
repair and growth of all the tissues of the body, the food 
must contain the proper amount of heat-producing material, 
as well as the materials which make bone, muscle, fat, etc. 
All these in the right proportions are seldom found in any 
one article of food. 

Into what four divisions, or classes, may articles of food 
be divided ? 

For convenience, articles of food may be divided into four 
classes: 1st, nitrogenous foods, or albumens; 2d, starches 
and sugars ; 3d, oils em&fatsj 4th, inorganic, or mineral 
foods. 

Ofiohat use are nitrogenous foods, or albumens? 
3 



34 BKIEF LESSONS ON THE HUMAN BODY. 

The nitrogenous foods, or albumens, are especially mus- 
cle-making foods. They are called nitrogenous foods 
because they are rich in nitrogen, an essential element in 
lean meat. They are called albumens, or albuminoids, 
because they contain a white substance called albumen. 
The white of an egg is pure albumen. The foods belong- 
ing to this class contain to some extent the elements neces- 
sary to form other kinds of tissues, yet we say that their 
particular use is to make muscle. 

Name the principal articles of food which may be classed 
as muscle-making foods, or albuminoids. 

Among the albuminoids, or the articles of food most 
useful for making muscle, are eggs, lean meat, milk (the 
cheesy part, or curd), peas, beans, wheat, barley, oats, and 
other grains. 

Of ivhat use are starches and sugars ? 

The starches and sugars contain carbon, oxygen, and 
hydrogen, but no nitrogen. Their use is to serve as a 
kind of fuel which is consumed by the oxygen in the body. 
The heat thus produced keeps the body warm, and gives to 
it the energy, or strength, by which it is able to perform 
its work. 

Name the articles of food tvhich are rich in starch or 
sugar. 

Starch is the important food substance in all vegetables. 
It is found abundantly in potatoes, rice, corn, wheat, barley, 
tapioca, arrow-root, etc. The sugars are derived from vege- 
tables. They are used for food in a nearly pure form, as 
sugar, candy, honey, etc., and are also taken to a small 
extent with milk and vegetables such as melons, beets, 
peaches, strawberries, grapes, pineapples, etc. 

Of what use are fats and oils ? 



FOOD AND DRINK. 35 

The use of the fats and oils is nearly the same as that of 
the starches and sugars ; that is, to produce heat and vital 
energy. Fats and oils produce about twice the amount of 
heat, or energy, as that produced by an equal amount of 
sugar or starch. 

From what foods are fats and oils obtained? 

Fats and oils are obtained mostly from fat meats, eggs, 
butter, and milk. They are also obtained in small quan- 
tities from nuts, oliyes, beans, and other vegetable foods. 

What are some of the inorganic, or mineral, substances 
found in the body ? 

Among the inorganic, or mineral, substances found in the 
body are water, lime, salt, iron, phosphorus, potash, and 
sulphur. 

Of tuhat use is tvater as a food? 

Water is present in all the tissues and in all the fluids 
of the body. About seventy per cent, of the weight of the 
body is water. Water keeps the blood thin so that it will 
flow more readily ; it helps to carry off waste matter ; it aids 
in digesting food ; and keeps the bones, muscles, and other 
tissues from becoming hard and dry. The body requires 
on an average about four and a half pounds of water per 
day. 

Of ivhat use are other inorganic, or mineral foods ? 

Lime is required by the body for bones and teeth. Salt 
is found in all the tissues of the body except the enamel of 
the teeth ; it is useful in aiding the digestion of other sub- 
stances. Iron and potash are found in the blood; phos- 
phorus and sulphur are found in the muscles and other 
tissues. 

From tvhat sources are inorganic, or mineral, foods 
obtained? 



36 BKIEE LESSORS ON THE HUMAN BODY. 

Water, besides being taken into the body in its pure 
form, is taken in with every kind of food, whether solid or 
liquid. For instance, bread is 37 per cent, water; fat beef, 
5L per cent.; lean mutton, 72 per cent.; potatoes, 75 per 
cent. ; turnips, 91 per cent. Salt is used as a seasoning for 
other foods. Lime is found in hard water, also in meat, 
milk, and vegetables. Iron is found in milk and eggs, and 
the same' may be said of phosphorus and sulphur. Potash 
exists in vegetable matter. 

Why does the quantity of food which a person requires 
vary ? 

From what we have already learned we may rightly con- 
clude that a man requires more food in youth than in old 
age, more during an active than a sedentary period of life, 
more in a cold climate than in a warm one, more in winter 
than in summer. 

What is the estimated daily amount of food and drink 
required by a healthy man of active habits ? 

The amount of food required daily by a healthy man of 
active habits is estimated to be about six pounds. Suppos- 
ing his food to consist of beefsteak, bread, potatoes, butter, 
and water, leaving out tea, coffee, and salt, the proper 
quantity of each would be about as follows : beefsteak, 8 
oz. ; bread, 20 oz.; potatoes, 30 oz. ; butter, 1 oz. ; water, 

37 oz. 



CHAPTER VIII. 

ORGANS OF DIGESTION. 

Name the organs of digestion. 

The organs of digestion are : the mouth and salivary 
glands, the stomach, the pancreas, the liver, and the intes- 
tines. 

What is the alimentary canal? 

The alimentary canal is the canal, or tube, formed by the 
organs of digestion, together with the passages which con- 
nect them. 

Describe the alimentary canal. 

The alimentary canal is about twenty-five feet in length. 
Its walls are composed mostly of muscles, and it extends 
from the mouth downward through the body. It is lined 
throughout its entire length by a thin, soft, moist, reddish 
skin, or membrane, called the mucous membrane. In and 
around it are hollow organs, called glands, which pour into 
it certain fluids, which help to dissolve the food and to fit 
it for entering the blood. 

Through what four processes must the food pass in order 
to build up, or nourish, the body? 

In order to give nourishment to the body the food must 
pass through four processes. First, it must be dissolved, 
or changed into a liquid in the alimentary canal, called 
digestion ; secondly, it must pass from the alimentary canal 
into the blood-vessels, called absorption ; thirdly, it must 



38 



BKIEF LESSOKS OK THE HUMAK BODY. 




Internal Organs. 



B, the trachea (windpipe). 

C, oesophagus (gullet). 

E, diaphragm. 

F, liver. 
1, spleen. 

D, stomach. 



G, intestines. 

U, heart, the pericardium being 
laid open. 
A, lungs. 
J, bladder. 



ORGANS OF DIGESTION. 39 

be carried to all parts of the body by the blood, called cir- 
culation ; fourthly, it must be takeu from the blood and 
changed into tissues, bone, muscle, fat, etc., called assimi- 
lation. 

WJiat is the object of digestion ? 

The object of digestion is to change solid food into a 
liquid, and to prepare all food for entering the blood. It is 
plain that food, in the condition in which it is eaten, could 
not be taken into the blood. There is no open passage-way 
from the alimentary canal to the blood-vessels. No food 
can get out of it unless it soaks through its walls, and in 
order to do this, it must be changed into a liquid. 

Of tohat use cere the muscles in the walls of the alimentary 
canal ? 

The muscles in the walls of the alimentary canal aid 
digestion in two ways. They force the food along, and 
knead it and mix it with the juices. 

What part of the ivork of digestion is performed in the 
mouth ? 

In the mouth the food is cut and ground by the teeth to 
such fineness that it can be readily swallowed and easily 
acted upon by the juices of the stomach. It is also mixed 
with the saliva of the mouth, which aids in swallowing, 
brings out the taste, and is a help to digestion. 

What is the office of the salivary glands, and where are 
they situated ? 

The office of the salivary glands is to secrete, or take 
from the blood, the fluid called saliva, which moistens the 
mouth. When we eat or taste something which we like, 
so much saliva is sometimes poured out that we say the 
" mouth waters." There are three pairs of salivary glands. 
The largest are called the parotid glands. They are sit- 



40 BRIEF LESSONS OK" THE HUMAN BODY. 

uated one in front and below the lower part of each ear. 
They are the glands which swell when we have the mumps. 
One of the other pairs is situated under the tongue ; they 
are called the sublingual glands. The other pair is situated 
under the lower jaw ; they are called the sub-maxillary 
glands. From each of these glands there are little tubes, 
called ducts, leading into the mouth. 

How does the saliva aid digestion ? 

The saliva moistens and softens the food, and to some 
extent dissolves it. It also acts upon the starchy matter 
in the food by changing it into a kind of sugar, which is 
quickly dissolved on entering the stomach. 

Describe the oesophagus. 

The oesophagus (ce-soph'-a-gus) is a muscular tube about 
nine inches long, leading from the mouth to the stomach. 
The muscles in the walls of the oesophagus extend round 
and round in a ring-like form, so that when one ring con- 
tracts it crowds the food on to the next. In this way it is 
pushed on until it reaches the stomach. 

What is the shape and size of the stomach ? 

The stomach is a pear-shaped bag, or pouch, which will 
hold about two quarts. When empty, it collapses, like any 
other bag. When full it is some ten or twelve inches long, 
and about four inches broad. 

Where is the stomach situated, and hoto many openings 
has it ? 

The stomach is situated across the upper part of the abdo- 
men, directly under the diaphragm, the larger end to the 
left side. It has two openings. The opening where the 
food enters is called the cardiac orifice. The other open- 
ing at the right end, where the food leaves the stomach and 
where the intestines begin, is called the pylorus (py-lo'-rus), 



ORGAKS OF DIGESTIOtf. 



41 



—a 




The Organs of Digestion. 



a, the oesophagus. 
&, the pancreas. 

c, the stomach. 

d, the spleen. 

e, the small intestine. 



/, the large intestine. 
h t the appendix. 
j, the gall-bladder. 
k, the liver. 
I, the pylorus. 



42 BKIEF LESSONS ON THE HUMAN BODY. 

or gate-keeper. It is so called because it closes so as to 
keep the food in the stomach until it is ready to pass out. 

Describe the walls of the stomach. 

The walls of the stomach are thin, soft, and flexible. 
They are composed of three coats, or layers. The outer 
coat is a layer of tough, fibrous tissue ; its rise is to give 
strength and firmness, and to hold the stomach in place by 
being attached to the back and sides of the abdomen. The 
middle coat is a muscular coat ; its use is to give motion 
to the contents of the stomach, keeping them well mixed. 
The inner coat of the stomach is called the mucous coat. 
It contains mauy blood-vessels, and the glands which con- 
stantly supply the stomach during the process of digestion 
with an important fluid called gastric juice. 

Describe the gastric juice. 

The gastric juice is a clear, almost colorless, fluid, with a 
sharp acid taste. It contains a peculiar substance, called 
pepsin. The acid and the pepsin are both necessary to the 
digestion of food in the stomach. The quantity of gastric 
juice which daily finds its way into the stomach varies con- 
siderably. It is estimated to be between five and fourteen 
pounds. 



CHAPTEE IX. 

OKGANS OF DIGESTIONS — CONTINUED. 

What is the office of the gastric juice ? 

The principal office of the gastric juice is to dissolve the 
class of foods which we have called albuminoids ; such as 
lean meat, cheese, eggs, and, in general, all animal matter. 
It has comparatively little effect upon starchy matter. 

What is the food in the stomach called after it has been 
acted upon by the gastric juice? 

The food in the stomach, after it has been acted upon by 
the gastric juice, is called chyme. Chyme is a pulpy, soup- 
like substance, of a grayish color. In it are fats and oils, 
as well as starchy matter, which have not yet been made 
soluble. 

How does the digested food escape from the stomach ? 

When the food has been properly changed into chyme, 
the muscles at the pylorus relax, and the partially digested 
food passes out in little jets into the duodenum, which is 
the first portion of the small intestines. The duodenum is 
so called because its length is about equal to the breadth of 
twelve fingers. 

What fluids are mixed with chyme after it enters the 
duodenum ? 

When the chyme enters the duodenum, two juices, the 
bile from liver and the pancreatic juice, are poured in and 
mixed with it. The walls of the intestines also secrete a 



44 BRIEF LESSONS ON THE HUMAN BODY. 

digestive fluid, which is mixed with the chyme as it passes 
along. 

What seems to be the use of the bile ? 

The chief use of the bile seems to be to digest the fats 
and oils in the food, upon which the gastric juice does not 
act. It also helps to separate the nutritious from the use- 
less parts of the food. 

Wliat is the use of the pancreatic juice ? 

The use of the pancreatic juice seems to be very much 
like that of the saliva. It acts chiefly upon starchy matter 
which has escaped the saliva, and changes it into sugar. It 
also helps to dissolve albuminoids which have not been 
digested by the gastric juice. 

Of what use is the intestinal juice? 

The infestinal juice is the fluid which completes the work 
of digestion. It seems to combine in one the properties of 
all the other digestive fluids. Like the saliva, it acts upon 
starchy matter ; like the gastric juice, it is a solvent for 
albuminoids ; and like bile, it has the power of rendering 
soluble fats and oils. Thus it seems that nature intends 
that this last fluid in the digestive tube shall perform all 
the work left undone by the others, and so prevent the 
waste of any part of the food. 

After the food in the intestines has been acted upon by all 
the digestive fluids, what is it called? 

After the food has been acted upon by all the digestive 
fluids, it is called chyle. Chyle is a white, milky liquid, and 
it contains in solution all the digestible portions of the food. 

Through what process must the food next pass? 

The digested or liquid food, called chyle, must now pass 
out of the alimentary canal into the blood. As has already 
been said, this process is called absorption. 



ORGANS OF DIGESTION. — CONTINUED. 45 

How does the digested food pass out of the alimentary 
canal into the blood % 

Digested food passes from the alimentary canal into the 
blood in two ways. First, by the minute blood-vessels in the 
walls of the stomach and intestines. Secondly, by the lac- 
teals, which are. small tubes leading from the inside of the 
intestines. 

Hoio does the absorption of food take place by blood- 
vessels ? 

The walls of the digestive canal, especially of the small 
intestines, are full of blood-vessels, and the liquid food 
rapidly soaks through them and enters immediately into the 
veins and capillaries. These capillaries and veins unite and 
form a large vein called the portal vein, which carries the 
blood containing digested food to the liver. After passing 
through the liver, it is gathered up by other veins, and so 
finds its way into the right side of the heart. 

How does absorption of food take place by the lacteals ? 

Opening through the inner lining of the intestines are 
myriads of little tubes called lacteals. These tubes are so 
called from a Latin word meaning "milky," and because 
they carry a white, milky fluid. These little tubes take 
the chyle from the intestines. After leaving the intestines 
they unite into larger tubes, until finally they form a single 
tube about the size of a goose-quill, called the thoracic duct. 
The thoracic duct carries the fluid upwards, along the 
back-bone, and pours it into a large vein in the neck, 
which empties it into the heart. 

After the digested food enters the blood, how is it car- 
ried to the different parts of the body ? 

After the digested food enters the blood it becomes a 
part of the blood, and is carried in the circulation to all 



46 BRIEF LESSONS ON THE HUMAN BODY. 

parts of the body, where the different elements in it are left 
wherever they are needed for the repairing or building up 
of tissues. This completes the third process through which 
the food must pass in giving nourishment to the body. 

What takes place in the fourth process, called assimila- 
tion ? 

In the process of assimilation each cell and tissue of the 
body takes from the blood and adds to itself the material 
necessary to its own nourishment and growth. Thus food 
is converted into bone, muscle, fat, skin, etc. 

What time is required to properly digest food? 

The time required to properly digest food varies from 
one to five hours. The health of the individual, and the 
amount, kind, and quality of food, are some of the causes 
which make a difference in the time required for digestion. 

Name some hinds of food tvhich are quickly digested. 

Among articles of food which are quickly digested are 
boiled rice, barley soup, sweet apples, raw eggs, tapioca, 
milk, custard, and oysters. 

Name some hinds of food'ivhich are not quickly digested. 

Among articles of food which are not quickly digested 
are fat pork, beef suet, boiled cabbage, cheese, fried beef, 
etc., and any others which are so compact that the digestive 
fluids will not readily enter and dissolve them. 



CHAPTER X. 

HYGIENE OF ORGANS OF DIGESTION. 

Mention some things ivhich must he observed in order to 
keep the organs of digestion in a healthy condition. _ 

In order to keep the organs of digestion in a healthy con- 
dition, we should be careful always to take as nearly as pos- 
sible the right quantity of food, not too much or too little ; 
it should be good in quality, not indigestible, stale, or 
adulterated ; it should be of the proper temperature, not 
too hot or too cold ; it should be properly chewed and 
mixed with the saliva of the mouth ; the juices of the 
mouth and stomach should not be too much diluted by 
drinking during meals ; the juices of the mouth and stom- 
ach should not be wasted or destroyed by chewing gum or 
tobacco, or by the use of alcohol, or food too highly sea- 
soned ; food should be taken at proper intervals ; pure air 
and exercise are also necessary to a keen appetite and good 
digestion. 

What harm is likely to come from not eating enough 
food? 

Every action causes some of the tissues of the body to 
waste away, or wear out. If the amount of food taken is 
not sufficient to repair the waste, the body loses weight, 
grows thin, becomes feeble, and finally diseased. 

Why is the quantity of food which a person requires 
greater during the period of growth ? 



48 BRIEF LESSORS ON THE HUMAN BODY. 

The quantity of food which a person requires is greater 
during the period of growth, because the food must not 
only repair the waste, but supply material for building new 
tissues. The same thing is true when the body has been 
emaciated by starvation or disease. 

How does exercise affect the quantity of food required? 

When exercise is increased or diminished, the quantity of 
food should be accordingly increased or diminished. This 
is true because exercise causes waste, and the quantity of 
food needed to repair the waste will depend upon the 
amount of exercise. 

Why is more food required in winter than in summer? 

A considerable portion of the food which we eat is ex- 
pended in keeping the body warm. The body has nearly 
the same temperature summer and winter ; but it would 
become colder in winter, if we did not eat more, or in other 
words burn more fuel in it, for the same reason that more 
fuel is required to keep our rooms warm in winter than in 
summer. Cold climates, likewise, demand more heat-pro- 
ducing food than warm ones. The Esquimau is fond of fats 
and grease, while the native of the tropics lives almost 
wholly on vegetables. 

Why should care he exercised in regard to the quantity of 
food, during sickness ? 

Sickness, or disease, means that some organs of the body 
are notable to do their usual amount of work. The failure 
of one set of organs affects, more or Jess, all others. Con- 
sequently sick persons have poor appetites, and great care 
has to be taken that the organs of digestion are not over- 
taxed by too much food. If the digestive organs are not 
able to supply the necessary fluids, and to perform the whole 
work of digestion, the food sours, and being imperfectly 



HYGIENE OF ORGANS OF DIGESTION. 49 

digested irritates the lining of the intestines, and thus weak- 
ens the body instead of strengthening it. 

What is the harm of eating too much food? 

The glands of the stomach are only able to secrete gastric 
juice enough to dissolve a certain amount of food. If more 
than this amount is eaten, a part of it, at least, must go 
imperfectly digested. Besides this, too much food gives the 
organs of digestion too much work to do, and as a natural 
consequence the glands are weakened by excessive action. 

Mliy are immature or over-ripe vegetables not good articles 
of food? 

Immature fruits and vegetables are not usually good arti- 
cles of food, because they are likely to be indigestible, and 
they lack the fully formed juices which make vegetable foods 
most valuable. In over-ripe fruit and vegetables the juices 
have decomposed and have formed other substances which 
are harmful. 

Why is it not safe to eat raw pork? 

It is not safe to eat ham, sausages, or any other form of 
pork in a raw or imperfectly cooked condition. The muscle 
of the pig often contains a minute animal parasite, or worm, 
called trichina spiralis. If taken alive into the human body, 
this worm multiplies with great rapidity and causes a pain- 
ful and serious disease. The life of the parasite and its 
ability to do serious harm are destroyed by proper cooking. 

What is the object of cooking food, and why should food be 
well cooked ? 

The object of cooking food is to improve its flavor, to 
make its temperature more nearly equal to that of the body, 
to soften it so that it can be more easily broken up by the 
teeth and more easily acted upon by the digestive fluids. 
The proper cooking of food is a matter of great importance. 
4 



50 BRIEF LESSONS OX THE HUMAN BODY. 

By improper cooking, its flavor may be spoiled, it may be 
made tough and indigestible, or its nutritive qualities may 
be destroyed. The best food may be made unhealthful by 
improper cooking. 

Why should food be eaten at a proper temperature? 

If food or drink be taken too hot, it is liable to injure the 
mucous membrane of the gums, mouth, and stomach. Such 
practice is a fruitful cause of soft gums, decayed teeth, sore 
moutli and indigestion. If food or drink is taken too cold, 
the cold food or drink takes so much heat from the stomach 
that the process of digestion is delayed. The natural tem- 
perature is about 100° F. To drink freely of ice-water 
might lower the temperature to 40°. It would take, perhaps, 
half an hour for the stomach to regain its natural tempera- 
ture. In the mean time the process of digestion would go 
on very slowly, and the food might become sour. 

Why should food he properly masticated? 

Food should be properly chewed, or masticated, in order 
that it may be well mixed with the saliva, and that it may 
be in a condition fine enough to be easily acted upon by the 
gastric juice and other fluids. Eapid eating is a violation of 
good manners, and of the laws of hygiene. 

Why is it harmful to take much drink ivith food? 

The natural fluid with which to moisten food in the mouth 
is the saliva. The saliva is an important digestive fluid, 
and, if any other fluid, as water, tea, or coffee, be used as a 
substitute, digestion will not be so rapid or perfect. Be- 
sides, the water will so dilute the gastric juice that the work 
of digestion will have to stop until a portion of the water 
has been absorbed. 

What harm to digestion comes from chewing gum or tobacco ? 

The chewing of gum, tobacco, or any other substance 



HYGIENE OF OKGANS OF DIGESTION. 51 

excites a flow of saliva into the mouth. This saliva,, not 
being used for moistening or digesting food, is wasted ; and 
besides, the glands, not being able to act constantly, are 
unable to supply more when needed. Indigestion is liable 
to be the result. 

What are some of the effects of alcohol upon the organs of 
digestion ? 

Many cases of dyspepsia are due to alcoholic drinks. Such 
drinks irritate the lining of the stomach and stimulate the 
flow of the gastric juice ; but the alcohol absorbs the water 
from the gastric juice, and so acts upon it as to diminish 
its solvent power, thus seriously interfering with the pro- 
cess of digestion. If the use of alcohol is great and long 
continued, a chronic inflammation of the inner coating of 
the stomach occurs ; the walls become thick and hard, 
and traces of ulceration are often found. The liver is also 
very liable to disease from the use of alcoholic drinks. 

Why should condiments and spices be used sparingly ? 

Condiments are substances which are used to sharpen the 
appetite, to give relish for food, and to stimulate the diges- 
tive organs. Pepper, mustard, horse-radish, pickles, fancy 
meat-dressings, and highly-seasoned sauces, may be classed 
as condiments. Their immoderate use injures the taste, in- 
flames the mucous membrane, excites an excessive secretion 
of the digestive fluids, and causes the consumption of more 
food than the body requires. 

Why should food be taken at regular intervals ? 

The organs of digestion, like all other organs of the body, 
must have periods of rest. Like all other organs, too, they 
do their work best when their tasks are done at regular 
periods. Eating between regular meals is a habit ruinous 
to the digestive organs, because it disturbs the chemical pro- 



52 BRIEF LESSONS ON THE HUMAN BODY. 

cesses which take place, and gives the stomach no time to rest. 
It is a habit, in many respects, similar to that of over-eating. 

Why is it well to rest for a little time just before and 
after eating ? 

When any part of the body is being vigorously exercised, 
the flow of blood and the nervous forces of the body are 
especially directed towards that part. This concentration 
cannot be suddenly changed to some other set of organs, 
consequently a little time should be given just before meals 
for gradually restoring the system to its natural condition. 
For the same reason, severe exercise and hard study just 
after a full meal are very apt to hinder digestion. After a 
full meal the vital forces of the body are engaged in helping 
the stomach digest food. If, in addition to this, they are 
required to help the muscles or brain, one or both will get 
imperfect service. Moderate exercise of the muscles, pleas- 
ant conversation, and a hearty laugh, are aids to digestion. 

Why does good digestion require pure air ? 

The organs of digestion in order to do their work well 
must have a plentiful supply of pure blood. In order to 
have pure blood we must breathe pure air. Hence poor 
ventilation is a frequent cause of indigestion. People who 
sleep in ill-ventilated rooms have little or no appetite for 
breakfast. 

NOTES AND SUGGESTIONS. 

Note 1. Collection of Specimens, — The principles which underlie the 
matter of our daily food cannot be too well understood. Children 
should be made familiar with all classes of food-stuffs, and the valuable 
elements in each. An interesting and valuable collection of specimens 
of such articles can be easily made. The specimens can be kept in 
glass bottles and should be neatly labelled. In class let pupils handle 
them, taste them, talk about them. 



NOTES AND SUGGESTIONS. 53 

2. Shoiv the Organic Substances in the Albuminoids. — The subject of 
foods and digestion, also, admits of many useful and interesting experi- 
ments. The albuminoids, or nitrogenous foods, contain one or more 
of the following organic substances : albumen, caseine, fibrine, gelatine, 
gluten, and legumen. Albumen may be shown as the white of an egg ; 
also by washing and squeezing a piece of lean meat in cold water with 
a lemon-squeezer, until nothing but a whitish stringy mass is left. 
The albumen has been dissolved in the water and may be coagulated 
by heating the water. The whitish stringy mass which was left is 
fibrine. To show caseine, pour some dilute acid, vinegar, or liquid 
rennet, into some milk. A whitish curd will be formed. This is 
caseine, the chief constituent of cheese. Gelatine may be obtained by 
boiling a bone for a long time. For instance, calves' feet are boiled to 
make jelly for the sick-room. Glue is simply gelatine obtained by 
boiling the bones, hoofs, horns, etc., of animals. Gluten may be 
shown by putting a small quantity of flour in a cloth and squeezing it 
in a basin of water. The gluten is the sticky substance remaining in 
the bag. If the water is allowed to stand, the starch will settle to the 
bottom as a white powder. If beans or peas in the pod be boiled for a 
time, they will finally become a sticky, pulpy mass. This pulpy mass 
is legumen. It resembles albumen in the egg, and gluten in flour. 

3. Shoiv Starch in Vegetable Foods. — The test for starch is a little 
tincture of iodine. This dropped into any mixture containing starch 
will turn it blue. Boil a little flour, rice, tapioca, or potato, in a test- 
tube, and add a drop of the tincture of iodine. It will quickly turn 
blue. In regard to specimens of sugars and oils, no suggestion is 
necessary. They can easily be obtained. 

4. Prove that Milk contains All the Necessary Elements for Food. — A 
calf fed upon milk alone will grow and thrive. He obtains from it all 
the materials necessary for making bones, muscles, fat, hair, skin, etc. 
That milk is a compound food may be shown by experiment. Take 
some milk " fresh from the cow/' place it in a tall glass vessel and let 
it stand for a few hours. Cream will then be found on the top. Take off 
the cream, and to the milk which is left add a little liquid rennet, acid, 
or vinegar, and a whitish curd will be found, leaving a watery liquid 
called xohey. The milk now has been separated into three parts, 
cream, curd, and whey. Cream is t\\efat in milk ; curd is the caseine, 
or nitrogenous part; and whey is milk-sugar and mineral matter 
dissolved in water. 



54 BRIEF LESSONS ON THE HUMAN BODY. 

5. Saliva changes Starch to Sugar.— Place in the mouth a small 
quantity of starch. Chew it slowly until it becomes thoroughly 
moistened. Notice that it has a sweet taste The same thing can be 
shown with a cracker or a piece of bread. 

6. The Mouth waters at the Thought or Sight of Food. — Take in your 
hand or think of some favorite article of food, especially if you are 
hungry, and note the flow of saliva. This is forcibly illustrated by 
cows, when they sometimes stand on the opposite side of a fence wait- 
ing for food which is being prepared in sight of them. The flow of 
saliva is often so great that it almost pours from their mouths in 
streams. 

7. Helps for showing the Anatomy of Digestion. — The position and 
arrangement of the organs of digestion can be quite well understood 
by the use of a manikin, or charts, or by a diagram on the blackboard. 
A good idea of the structure of the walls of the stomach may be 
obtained by examining a piece of a pig's stomach, which somewhat 
resembles the human stomach. Such a specimen can easily be obtained 
from the butcher. The liver and pancreas can be obtained and 
examined in the same way. 

8. How a Knowledge of Many Facts regarding Digestion was ob- 
tained. — In 1822 a French Canadian, Alexis St. Martin, was wounded by 
a gun-shot which tore away the flesh of the abdomen and made a hole 
in the stomach. St. Martin recovered, but the hole did not close. A 
piece of flesh hung over the opening which could be lifted up so as to per- 
mit a look into the stomach. The physician, Dr. Beaumont, tried many 
experiments upon St. Martin, and by these experiments many things 
relating to digestion were found out. Experiments upon animals have 
also added greatly to our knowledge of the laws of digestion. 

9. Comparative Anatomy of Organs of Digestion. — The teacher can 
orally supplement the lesson with many interesting facts by compar- 
ing the digestive organs of various animals. The peculiarities of the 
digestive apparatus of the cow, the hen, the snake, will especially be 
of interest. 

10. Effect of Alcohol on Albuminous Food.— Put the white of an egg 
into a small quantity of alcohol. Stir the egg and the alcohol together 
for a few minutes. The egg will begin to harden and have a cooked 
appearance. The effect of alcohol upon such food is to hinder, not to 
help, digestion. 



CHAPTER XL 

THE BLOOD AND ITS CIRCULATION. 

What is the blood f 

The blood is the red liquid which circulates through the 
different parts of the body. Blood has a saltish taste. It 
is a little heavier and thicker than water. 

What are the uses of the blood ? 

The uses of the blood are, to carry digested food to all 
parts of the body, to keep up the warmth of the body and 
to provide it with moisture, to gather and convey waste 
matter to places where it may be discharged, and to carry 
oxygen to such tissues as require it. 

Does the blood circulate through every part of the body ? 
What is the average quantity of blood in the human body? 

The blood circulates through every part of the body 
except the outer part of the skin, the nails, enamel of the 
teeth, and cornea of the eye. The average quantity of 
blood in the human body is about eighteen pounds. 

Of luliat is the blood composed? 

The blood is composed of an almost colorless fluid called 
plasma, in which float a great multitude of little circular 
bodies, or discs, called corpuscles. The corpuscles are of two 
kinds, red and white. There are about four hundred times 
as many red corpuscles as white ones. The individual cor- 
puscles can be seen only by the aid of a microscope. The 
red corpuscles are so numerous and so closely packed 
together that they make the entire substance of the blood 
to appear to be red. It is said that five million corpuscles 
will float around in a single drop of blood. 



56 



BRIEF LESSONS ON THE HUMAN BODY. 




View of the Heart with the Circulatory Apparatus, 



THE BLOOD AND ITS CIRCULATION. 57 

1, the heart ; 2, the pulmonary artery; 3, the inferior or ascending 
vena cava ; 4, the superior or descending vena cava ; 5, the aorta ; 
6, its point of division ; 7, point of division of left common iliac 
artery ; 8, external, 9, internal, iliac arteries ; 10, left common carotid, 
with internal jugular vein lying to its outer side ; 11, left subclavian 
artery and its continuation, the axillary ; 12, the brachial, 13, the 
radial, 14, the anterior, tibial arteries ; 15, long saphenous vein ; 
16, cephalic vein of right arm ; 17, basilic vein ; 18, ramifications of 
pulmonary vein and arteries in the left lung. The direction of the 
blood current is indicated by the arrows. The veins are darker than 
the arteries. 

Of what is the plasma composed f 

The plasma, or nutritive fluid, is composed of water 
richly laden with materials derived from the food. It, in 
fact, contains all the elements of which the body is com- 
posed. 

Of what use are the red corpuscles ? 

The red corpuscles are carriers of oxygen. They take 
oxygen from the air in the kings and carry it for distribu- 
tion to the various tissues of the body. The office of the 
white corpuscles is not certainly known. They are sup- 
posed to change after a little into red ones. 

What takes place ivhen Hood is exposed to the air ? Of 
what advantage is this ? 

If blood is exposed to the air, it immediately clots, or 
coagulates. That is, it thickens and assumes a semi-solid 
form. This coagulation of the blood saves us from bleeding 
to death when we are wounded. The clots which form stop 
rip the mouths of the cut blood-vessels. 

What is the effect from loss of Hood? 

Loss of blood causes weakness, and, if very great, faint- 
ing. During a fainting-fit the heart nearly stops its action, 
which makes the blood flow more slowly, and gives it a 



58 BRIEF LESSONS ON THE HUMAN BODY. 

chance to coagulate. Thus a fainting-fit may save life. A 
man's body contains six or eight quarts of blood. The loss 
of more than half of this would surely cause death, and a 
very much smaller amount might do so. 

What is meant by the circulation of the blood? 

The blood is in constant motion during life. It is con- 
tinually flowing from the heart toward the various organs of 
the body, and from these organs back to the heart again. 
This movement is called the circulation of the blood. 

By whom, ivas the circulation of the blood discovered ? 

The circulation of the blood was discovered by Dr. Will- 
iam Harvey, an Englishman, in the year 1619. 

What length of time is required for the complete circula- 
tion of the blood ? 

In some cases a drop of blood goes the complete round 
of the body in about twenty-two seconds. The entire blood 
in the body probably completes this circuit inside of two 
minutes. 



CHAPTER XII. 

THE ORGANS OF CIRCULATION. 

Name the organs of circulation. 

The organs of circulation are the heart, the arteries, the 
capillaries, and the veins. As we study these organs, we 
shall find that the heart is a central forcing-pump, and 
that the arteries, veins, and capillaries are pipes which 
either carry the blood from the heart or back to it again. 

Describe the heart. 

The heart is a hollow, muscular organ, pear-shaped, and 
situated in the centre of the chest, above the diaphragm, 
with the small end pointing down, and to the left. It is 
about as large as the closed fist. It is a double organ, hay- 
ing a partition-wall extending through the centre from top 
to bottom, which separates the right side from the left. 
Each of these sides has two hollow chambers or cavities. 
The upper cavity on the right side is called the right auri- 
cle ; the upper one on the left side is called the left auricle. 
The lower cavities, in the same way, are called the right 
ventricle and the left ventricle. The walls of the ventricles 
are thicker and stronger than the walls of the auricles, and 
those of the left ventricle are much stronger than those of 
the right ventricle. The right auricle opens by a valve into 
the right ventricle, and the left auricle opens by a valve 
into the left ventricle ; but there is no connection between 
one side of the heart and the other. The heart is, in fact, 
two pumps, each with its own work to do. 



60 BRIEF LESSONS ON THE HUMAN BODY. 

Describe the valves of the heart. 

The openings between the auricles and ventricles are pro- 
vided with little swing-doors, called valves, which open to 
allow the blood to flow into the ventricles ; but close, if it 
attempts to flow back into the auricles. The valve between 
the right auricle and the right ventricle is composed of three 
thin flaps of tough membrane, and is called the tricuspid 
(three-pointed) valve. The valve between the left auricle 
and the left ventricle consists of two such flaps, and is called 
the mitral valve, from the supposed similarity to a bishop's 
mitre. The passages from the ventricles into the arteries 
are closed by half-moon-shaped valves, called semi-lunar 
valves. 

By what is the heart surrounded ? 

The heart is surrounded by a loose sac or membrane, 
called the pericardium. The pericardium is soft and 
smooth, and gives out an oily fluid which prevents friction 
and keeps it moist and pliable. 

Wliat Hood-vessels are connected with the heart ? 

Two large veins pour the impure blood as it returns 
from all parts of the body into the right auricle. From the 
right ventricle the pulmonary artery carries this blood to 
the lungs to be purified. Into the left auricle the pulmo- 
nary veins pour the pure blood as it returns from the lungs. 
From the left ventricle a large artery, called the aorta, 
takes the blood, and, through its various branches, distrib- 
utes it to all parts of the body. 

Describe the arteries. 

The arteries are tube-like canals which carry blood away 
from the heart. Their walls are made of tough fibrous 
materials, so that they can endure the necessary strain with- 
out being broken. The walls also are elastic, and thus they 



THE ORGANS OF CIRCULATION. 61 

aid the heart in forcing the blood along. One artery (the 
pulmonary) with its branches conveys the blood to the 
lungs. The other (the aorta) with its branches extends to 
every part of the body. These branches as they get farther 
from the heart become smaller and more numerous, until 
finally they form throughout the entire body a complete net- 
work of hair- like tubes, called capillaries. They are, how- 
ever, smaller than any hair, and can only be seen by the use 
of a microscope. 

Describe the veins. 

The veins are the return-pipes which take the blood back 
to the heart. They start from the capillaries and grow 
larger and less numerous until finally they form two large 
veins, the vena cava ascending, and the vena cava descend- 
ing, which empty into the right auricle. The veins are 
provided with valves so arranged that the blood can only 
flow towards the heart. The walls of the veins are not as 
thick and strong as those of the arteries. 

How do veins and arteries differ as to situation ? 

The veins generally lie near the surface of the body, just 
under the skin. They may be seen in the backs of the 
hands and in the temples. The arteries, especially the large 
ones, are mostly situated far beneath the surface, often run- 
ning close to the bones and through safe passage-ways. 
This arrangement possesses the advantage of safety, as there 
is more danger from injury to an artery than to a vein. 

Mention some other differences letiveen veins and arteries* 

Arteries carry blood from the heart ; veins carry it 
towards the heart. The walls of the arteries are thicker 
and firmer than those of the veins. Veins have at inter- 
vals valves which prevent the blood from flowing backwards; 
arteries do not. 



62 BRIEF LESSONS ON THE HUMAN BODY. 

What artery carries impure blood ? What veins carry 
pure blood? 

It is generally said that arteries carry pure blood, and 
that veins carry impure blood ; but there are two excep- 
tions. The pulmonary artery carries impure blood from 
the right ventricle to the lungs, and the pulmonary veins 
carry pure blood from the lungs to the left auricle. 

In case of a tvound, hoiv can we tell whether flowing blood 
is from a vein or an artery ? 

Blood flowing from a vein is of a dark color, that from 
an artery is lighter. Blood from a vein flows in a steady 
stream ; from an artery it flows in jets, as the heart beats. 
The flow of blood is more easily stopped from a vein than 
from an artery. 

Describe the capillaries. 

The capillaries are a fine net-work of tubes which con- 
nect the arteries and veins. They are so much a part of 
the arteries and veins that it is impossible to tell where an 
artery ends, and where a vein begins. It is in the capilla- 
ries that the blood gives up the materials for repairing 
waste and for building new tissues. Here also the blood 
receives waste matter and particles of worn-out tissue which 
are to be carried back and cast out of the body through the 
lungs. 

Trace the course of the blood through its complete circula- 
tion. 

In circulation the blood passes from the right auricle into 
the right ventricle, from the right ventricle through the 
pulmonary artery to the lungs, from the lungs through the 
pulmonary veins to the left auricle, from the left auricle 
into the left ventricle, from the left ventricle into the 
arteries, from the arteries into the capillaries, from the 



THE ORGANS OF CIRCULATION. 



63 




A Diagram of the Circulation. 



1, right auricle. 2, right ventricle. 0, left auricle. 10, left ven- 
tricle. 4, 5, pulmonary arteries. 7, 8, pulmonary veins. 11, 12, 13, 
13, aorta and its branches. 6, 6, pulmonary capillaries. 14, 14, 
systemic capillaries. 17, tricuspid valves. 19, mitral valves. 18, 
20, semi-lunar valves of the pulmonary artery and the aorta. 



G4 BRIEF LESSONS ON THE HUMAN BODY. 

capillaries into the veins, from the veins back again into 
the right auricle of the heart, thus completing the circu- 
lation. 

What is the force which propels the blood in its cir dela- 
tion ? 

The force which propels the blood through the system is 
the muscular power exerted by the contraction of the walls 
of the heart, aided by the elasticity of the arteries and their 
surrounding tissues. 

What is the average rate of the pulsations of the heart ? 

The average number of heart-beats in an adult man is 
about seventy-two per minute, but many circumstances will 
increase or decrease its rate of action. The number varies 
with age, sex, and individuals. Napoleon's pulse is said to 
have been only forty. It is not strange to find a natural 
pulse at one hundred or more. The will, however, has no 
pow 7 er either to increase or decrease the number. 

In cases of sickness, ivhy does the physician examine the 
pulse ? 

Nearly every disease modifies in some respect the condi- 
tion of the pulse. Consequently its rate, regularity, force, 
and fulness will, to the trained touch of the physician, be 
a good index of the physical condition of the patient. 

Mention some things ivhich hasten the circulation. 

The blood flows more rapidly during digestion, or when 
the body is under the influence of stimulants, as alcohol, 
tobacco, or coffee. Mental or physical exercise quickens 
the action of the heart. Excitement, inflammation, or 
fever causes the heart to beat more rapidly. 

Mention some things ivhich retard the circulation. 

The blood flows more slowly during sleep, or when the 
body is under the influence of narcotics. Tight clothing 



THE ORGANS OF CIRCULATION. 65 

obstructs the flow of the blood. It is also retarded by fear, 
or by any cause which produces fainting. 

How does the blood keep the body to arm ? 

The natural temperature of the body is about 98° F. 
summer or winter ; this temperature rarely varies more 
than a degree or two, except in disease. How this heat is 
maintained is a question not fully understood. We can 
perhaps explain it partially as follows : The element in 
coal, or wood, which burns in our stoves and produces heat, 
is carbon, or charcoal. Air enters the stove through the 
damper. When the fire is kindled, the oxygen of the air 
combines with the carbon of the coal or wood, and pro- 
duces heat and light. Whenever carbon and oxygen unite, 
heat and carbonic acid are produced. If the combination 
takes place slowly, no light is produced. It is undoubtedly 
true that our bodies are kept warm by a similar combination 
of carbon and oxygen. The fuel of the body is the carbon, 
taken in the form of sugar, starch, and fat. The oxygen 
is obtained from the air we breathe. The combining, or 
burning, does not take place in any one part of the body ; 
but is slowly going on in the blood throughout all parts of 
the body. This makes the blood warm. The circulation 
helps to equalize the heat throughout the body, as the veins, 
arteries, etc., are so many pipes containing warm blood 
which. gives up its heat to surrounding tissues. 
5 



CHAPTEE XIII. 

HYGIENE OF ORGANS OF CIRCULATION. 

What may be said in regard to the number of diseases 
which belong to the organs of circulation ? 

Although constantly in use and easily affected by mental 
conditions and muscular exercise, the organs of circulation 
are affected by few diseases. And in many cases where dis- 
eases seem to belong to the heart, the real difficulty lies in 
other organs. The heart is wonderful for its vitality. It is 
the last organ of the body to part with its vital energy. 

Name some things which should be observed in the care of 
the organs of circulation. 

Among the things to be observed in the care of the or- 
gans of circulation are the following : Care should be taken 
to avoid sudden changes in temperature ; tight clothing 
should not be w r orn ; great excitement, anger, or any violent 
exercise of mind or body should be avoided ; hemorrhages 
from wounds, etc., should be guarded against ; there should 
be no excessive use of tobacco, alcohol, or unnecessary drugs 
of any kind ; care should be taken to prevent the introduc- 
tion of poisons, animal or vegetable, through the broken sur- 
face of the skin by absorption ; the body should have at all 
times a proper amount of physical exercise, plenty of sleep, 
good food, and pure air. 

Why should sudden changes of temperature be avoided 1 ? 

The blood-vessels are contracted by cold, consequently a 
chill drives the blood to other parts. The chilled parts are 



HYGIENE OF ORGANS OF CIRCULATION. 67 

weakened, while the other parts are congested, or over- 
burdened with, blood. Congestion of the lungs from sudden 
cold is a frequent and dangerous occurrence. Exposure to 
intense heat, whether of the sun or of a furnace, causes a 
sudden prostration known as sun-stroke. The danger lies 
in the congestion which occurs in the internal organs. 

Hoiv does tight clothing affect the circulation of the 
Mood? 

Compression of any kind hinders the free circulation of 
the blood. Tight clothing about the waist interferes with, 
the action of the heart and lungs. Tight shoes cause cold 
feet. The tight dressing of the neck deprives the brain of 
the necessary amount of blood, and also hinders the free 
return of impure blood from that organ. This last is an 
item of great importance to brain- workers, and to persons 
who are inclined to any brain disease. 

Why should excitement of mind, or violent exercise, be 
guarded against ? 

Violent physical exercise, like running to catch a train, 
greatly increases the action of the heart, and sometimes to 
such an extent that it forces blood into the lungs faster than 
the lungs can get rid of it. This clogs the lungs, causing 
difficult breathing, and in some cases, the rupture of a blood- 
vessel, and dangerous bleeding from the lungs. Excitement, 
anger, fright, etc., if sudden and intense, frequently check 
the action of the heart so suddenly as to produce fainting, 
or swooning. The cause is that the brain has been sud- 
denly deprived of its supply of blood. Persons have died, 
instantly, in a fit of anger. 

What are hemorrhages, and how should they be treated? 

A hemorrhage is the losing of blood, either from a vein 
or an artery. If the blood from a wound flows in spurts and 



68 BRIEF LESSONS ON THE HUMAN BODY. 

is of a bright red color, it is from an artery. If it is dark- 
colored and flows in a steady stream, it is from a vein. If 
the bleeding is from an artery, put a tight bandage, or other- 
wise apply pressure, on the side of the wound towards the 
heart. If from a yein, apply the pressure on the side of the 
wound away from the heart. 

In what ivay does tobacco affect the circulation of the blood ? 

Tobacco is a poison, and its use, especially by the young, 
is attended with more or less danger. It is probably true 
that there are few people who use it habitually that do not 
suffer injury by it. It causes nausea, vomiting, dizziness, 
and weakness. Its prolonged and excessive use produces 
an irritability and weakened condition of the heart, known 
to physicians as the " tobacco heart. " When a boy first 
tries to use tobacco, it makes him very sick. If you should 
feel of his pulse then, you would find it weak. This means 
that the poison of the tobacco has partially paralyzed, or 
weakened the action of the heart. It is said, also, that 
tobacco injures the blood corpuscles. 

How does alcohol affect the circulation of the blood ? 

Alcohol hastens the circulation of the blood, and causes 
congestion of the blood-vessels. It increases the work of the 
heart, and thus exhausts its power. It is said that two 
ounces of alcohol per day will increase the work of the heart 
four per cent. Alcohol also softens the muscular fibres of 
the heart, and weakens it by changing the fibres into fat. 
It so acts upon the blood corpuscles as to reduce their 
cai3acity to absorb oxygen and carry out carbonic acid, etc. 
The walls of the blood-vessels also are weakened by the use 
of alcohol, and when from the same cause the blood-vessels 
of the brain are overcharged, they are liable to break, caus- 
ing apoplexy. 



HYGIENE OF ORGANS OF CIRCULATION. 69 

What error is often committed in the use of drugs for 
"purifying the blood" ? 

Many people regard the blood as the source of all diseases, 
and "to purify the blood" is, as they believe, the cure. 
Consequently quacks have been able to make fortunes by 
selling medicines, recommended for this jmrpose. The 
nature of the disease and the proposed remedy should be 
well understood before the taking of any medicine, and 
especially medicines which profess to cure almost everything 
by "purifying the blood." 

How is there danger of absorbing poisons through the sTcin ? 

Poisons are frequently taken into the blood through the 
skin, especially if there is a break in the cuticle, or outer 
skin. Persons often poison their hands with common wood- 
ivy. Painters absorb so much lead through the pores of 
their hands that they are sometimes attacked with colic. 
Contagious diseases are sometimes taken in this way. Cos- 
metics, hair-dyes, etc., are dangerous, because they often 
contain poison which may be absorbed into the system. 

Why does a healthy condition of the blood and organs of 
circulation require proper exercise ? 

Exercise of the muscles is not only a means of health to 
the muscles themselves, but to the entire system. Such 
exercise produces pressure upon the blood-vessels, and in- 
creases the force and rapidity of the circulation, thus pro- 
moting the consumption of oxygen by the tissues and the 
escape of carbonic acid and other waste products. 

Why does a healthy circulation require sleep ? Good food? 
Pure air ? 

All parts of the body share, directly or indirectly, in the 
benefits of sleep. Repair and waste are going on at all 
times, whether we are awake or asleep ; but during waking 



70 BEIEF LESSON'S ON THE HUMAN BODY. 

hours waste is greater than repair, while during sleep repair 
is far greater than waste. The heart and organs of circula- 
tion are less active during sleep, consequently they share in 
the benefits of the period of rest and repair. 

The materials which compose the blood are all obtained 
from the food, therefore good blood is dependent upon good 
food. 

We say that the blood is purified by being mingled with 
the air in the delicate cells of the lungs. The purifying ele- 
ment of the air is its oxygen. If the air lacks oxygen, the 
blood stagnates, the heart acts slowly, waste matter is not 
cast off, but remains in the blood and obstructs the whole 
system. 

NOTES AND SUGGESTIONS. 

Note 1. Use of Microscope to Examine Corpuscles. — A microscope 
of moderate power is sufficient to show the corpuscles of the blood. 
The white corpuscles will not be so readily discovered as the red ones. 
A drop of blood can be obtained for such an examination by winding a 
string tightly around the finger and then pricking the finger with a 
needle. It will be of interest to examine the blood of two or three 
other animals in this connection. The shape and size of corpuscles 
will be found to differ in various animals ; but in the case of most of 
the domestic animals, it will be hard for the unskilled observer to dis- 
tinguish them from those of man. 

2. How to Study Clotting of the Blood. — This may be done by 
placing the blood of a sheep, or of an ox, in a deep glass dish. After 
a little time clots will form and will lie in the centre of a light yellow 
fluid. The clot contains the globules, fibrine, and most of the coloring 
matter of the blood. Fibrine may be seen in the fibrous filaments 
which remain after washing a clot of blood in water. The yellowish 
fluid contains water, salts, and a little coloring matter. 

3. Circulation in a Frog's Foot. — The showing of the circulation 
of blood in the membrane of a frog's foot is an important and inter- 
esting object lesson. The frog may be tied up in a wet cloth, leaving 



NOTES AND SUGGESTIONS. 71 

one of his hind-legs outside. By attaching a cotton thread to two of 
his toes, and by the exercise of a little skill, his foot may be brought 
and fastened so that the membrane will lie under the object-glass of 
the microscope. 

4. Dissect a Sheep's Heart. — A sheep's heart with lungs attached 
may be had from the market. Its dissection before the class will prob- 
ably give pupils a better idea of the structure of the heart than can be 
obtained in any other way. Show pericardium, auricles, ventricles, 
valves, veins, and arteries. It would be well for the teacher to per- 
form at least one such dissection, before undertaking to do it before 
the class. 

5. To Find the Pulse. — Pupils should be taught to find and to 
count the pulse in their own wrists, also in the wrists of others. 
Every person should know the rate of his pulse when in a state of 
health, in order that he may know when an increase or decrease 
becomes an evidence of disease. 

6. Proofs that the Blood does Circulate. — People lived for thou- 
sands of years before it was discovered that the blood was in motion. 
When Dr. William Harvey in 1619 announced that it did circulate, 
he was not believed, and was subjected to ridicule and persecution. 
But the fact remained, and is now universally known. As proofs, it 
may be mentioned, that if certain chemical or coloring matter be put 
into the blood-vessels on one side of an animal, it will in a few sec- 
onds appear in the blood-vessels on the other side. In the case of the 
frog the blood can be seen in circulation. The beating of the heart 
and the motion of the pulse are confirming evidences. 

7. Transfusion of Blood. — Persons are often prostrated and some- 
times brought to the point of death by loss of blood. In such cases 
blood from the veins of a strong healthy person, or from an animal, is 
sometimes passed into the veins of the person prostrated. This oper- 
ation is called transfusion of blood. It was first performed about two 
hundred years ago, and it was then even believed that old people 
might be restored to the strength of youth by its use. Several deaths 
occurred from the operation, and it fell into disrepute. During the 
last few years it has been revived with good results. Better knowledge 
of the subject, and better surgical appliances, have nearly removed the 
danger from its use. It will not, however, overcome the effects of old 
age, but it will in certain cases save life. 



72 BKIEF LESSONS ON THE HUMAN BODY. 

8. Vitality of the Heart. — The tissues of the heart are remarkable 
for their vitality. This is especially shown in the case of some ani- 
mals. The heart of a turtle will pulsate, and its blood will circulate 
for a week or more after its head is off. The heart may even be taken 
out of the body, when it will continue to throb regularly for hours. 
The heart of an alligator, or a frog, or a snake, is likewise remarkable. 

9. Some Animals are Called Cold- Blooded. — The blood of reptiles 
is much cooler than that of mammals and birds. The heart of a reptile 
has only three cavities instead of four, two auricles and one ventri- 
cle. Consequently, pure and impure blood are mixed in this ventricle, 
and the blood is not so perfectly oxidized. The blood of fishes is also 
cold. Fishes use little oxygen. What they get is obtained from the 
air in the water. Fishes have hearts with only two cavities. The 
blood is forced by these to the gills, which serve as lungs, and from 
these it is distributed immediately to the different parts of the body. 

10. Ancient Idea of the Heart. — The ancients thought the heart to 
be the centre of the affections, the seat of courage, faith, love, and all 
the other virtues. Modern science has robbed it of its romance, but 
many words in common use are left to remind us of this fanciful the- 
ory. We say in case of grief, " heart-broken ;" a heart is a symbol 
for the sentiment of love ; one person is " heartless/' another is " Mnd- 
hearted" we learn our lessons " by heart," etc. The word '• courage" 
is from cor, meaning the heart. 



CHAPTER XIV. 

ORGANS OF RESPIRATION. 

What is meant by respiration ? 

Eespiration is the act of breathing. It consists of two 
operations — taking in the air, called inspiration ; and driv- 
ing out or expelling the air/ called expiration. 

What are the objects of respiration ? 

The objects of breathing or respiration are, to provide 
fresh oxygen to be combined with the carbon in the blood 
in order to keep up the warmth of the body and aid in the 
assimilation of food ; to carry off waste products of the 
body, as carbonic acid and watery vapor ; and, indirectly, 
to give voice, or the power of speech. 

Name the organs of respiration. 

The organs of breathing or respiration are the larynx, 
trachea, and the lungs. The lungs constitute the chief 
organ of breathing. The trachea and its branches are sim- 
ply pipes which make a passage-way for the air. The 
larynx, situated at the top of the trachea, is really the 
organ of voice. 

Describe the larynx. 

The larynx is a small, triangular, cartilaginous box, situ- 
ated just below the root of the tongue, and at the top of 
the trachea, or windpipe. The front of the larynx pro- 
duces the prominence in the neck, sometimes called Adam's 
apple. The opening from the throat into the larynx is 
called the glottis, and over this opening is a spoon-shaped 



74 



BRIEF LESSORS ON THE HUMAN BODY. 




The Lungs. 



a, the left lung. 
&, the right lung. 

c, the windpipe. 

d, the heart. 



e, the great artery carrying blood 
to the lungs. 

/, the great vein. 

g, the great artery carrying blood 
to the body. 



ORGANS OF RESPIRATION. 75 

lid called the epiglottis, which opens when we breathe ; but 
closes when we try to swallow, so that the food passes over 
into the oesophagus. In the larynx, attached to its sides, 
are bands of membrane, called vocal cords, by the vibrations 
of which voice is produced. 

Describe tile trachea, or windpipe. 

The trachea, or windpipe, is a cartilaginous tube extend- 
ing from the larynx to the lungs. It is four or five inches 
long and about three-fourths of an inch in diameter. It 
is composed of rings of cartilage, connected and covered 
by muscular fibres. These rings serve to keep the tube 
open for the passage of air. At the lower end the trachea 
divides into two branches, called bronchi, one of which leads 
to the right lung, and the other to the left lung. As they 
enter the lungs these branches again divide into smaller 
tubes, called bronchial tubes. These keep on dividing until 
they are not more than T1 ^y of an inch in diameter. They 
end in air-cells. 

Describe the lungs. 

The lungs are two large, pinkish, spongy organs situated 
in the cavity of the chest, one on each side, with the heart 
between them. The right lung is larger than the left, and 
consists of three parts, or lobes. The left lung has only two 
lobes. In the lungs are thousands of very small blood- 
vessels, so arranged that each one is completely surrounded 
by air. The oxygen of the air enters the blood by passing 
through the thin walls of these blood-vessels, and carbonic 
acid and watery vapor escape from the blood in the same 



Describe the covering of the lungs. 

A double membrane, called the pleura, forms a covering 
for the lungs. One of these membranes is attached to the 



76 BRIEF LESSONS OK THE HUMAN BODY. 

walls of the chest, and the other to the lungs. These layers 
of membrane secrete an oily fluid which lubricates them so 
that they glide upon each other with the utmost ease. 

With what are the air-tubes lined? 

All the air-tubes, including those of the nose and lungs, 
are lined w T ith an extremely sensitive and delicate lining, or 
mucous membrane. This membrane is so sensitive that it 
will not permit the presence of anything except pure air. 
A particle of food, a drop of water, or anything offensive in 
the air, coming in contact with it, irritates it, causing a 
violent cough, which is the effort of nature trying to expel 
the trespassing particles. 

How does the air reach the larynx ? 

The air reaches the larynx through the nostrils or through 
the mouth. The nostrils, however, are the true breathing 
passages. They are especially fitted to warm, cleanse, and 
moisten the inhaled air. They open into the upper part of 
the throat by two openings, similar to those in the nose. 

Why is it better in breathing that the air should pass 
through the nostrils? 

The air in passing through the nostrils is warmed and 
moistened because the passage-way is long and narrow, and 
the air comes in contact with a large extent of moist, warm 
surface. Besides this, there are hairs- just within the nos- 
trils, and hair-like filaments on other portions of the nasal 
cavity, which keep out dust and other foreign matter. If 
we breathe through the mouth, the air passes into the lungs 
without being warmed, it dries the throat, and is more liable 
to carry to the lungs dust and other impurities. 



CHAPTER XV. 

KESPIKATIOST A^D VOICE. 

What is the composition and use of the air ? 

Common air is mainly composed of two gases, oxygen 
and nitrogen, mixed in about the proportion of one part in 
volume of oxygen to four parts of nitrogen. It also contains 
small quantities of carbonic acid and watery vapor. Oxygen 
is the important element in the air. It enters into the com- 
position of all animal and vege table matter. The want of a 
fresh supply of it for five minutes would cause death. Nitro- 
gen is not used either by animals or plants ; neither is it 
injurious to them. Its use is to dilute the oxygen. Car- 
bonic acid is not used by animals, while j)lants thrive in it. 
Air containing more than a certain amount of carbonic acid, 
four or five per cent., acts as a poison to animals. Animals 
take in oxygen and give off carbonic acid, while plants take 
in carbonic acid and give off oxygen. Thus each serves the 
other. 

How is the air made to enter the lungs ? 

The lungs are not muscular, consequently they have no 
power to act for themselves, but by the action of the muscles 
of the w r ails of the chest and the diaphragm (a broad mus- 
cular partition between the chest and the abdomen) the 
cavity of the chest is enlarged. The lungs, consisting 
largely of little air-cells and air-tubes, are elastic ; and when 
the cavity of the chest expands by the raising of the ribs 



78 BKIEF LESSONS ON THE HUMAN BODY. 

and by the descent of the diaphragm, the lungs expand 
also, the air-cells open, and the outside air rushes in to fill 
them, just as air enters a bellows when its walls are sep- 
arated. 

How is the air expelled from the lungs? 

Attached to the ribs is another set of muscles which pull 
the ribs downward, the diaphragm also is pushed upward 
against the lungs by the contraction of the muscles of the 
abdomen. By these movements the cavity of the chest is 
greatly diminished, and the air is pressed out of the lungs 
through the bronchi, trachea, and nostrils. 

What is the average number of respirations per minute in 
an adult ? 

In health, the average number of respirations per minute 
by an adult is about eighteen. The number is greater in 
women and children than in men. The number is increased 
by exercise, food, and stimulants, while it is diminished by 
inactivity, starvation, and mental depression. 

Row does breathing purify the blood and nourish the 
body ? 

The air taken into the lungs by breathing purifies the 
blood in two ways, by taking out waste matter and by 
supplying fresh oxygen. A portion of the oxygen of each 
breath passes through the walls of the air-cells and of the 
capillaries in the lungs, and enters the blood. In the blood 
it joins itself to the red corpuscles and is carried to the 
heart and out through the arteries to the capillaries in all 
parts of the body. Here it leaves the corpuscles and becomes 
a part of the material which helps to nourish and build up 
surrounding tissues. As the blood discharges its load of 
oxygen from the capillaries, it takes up at the same place 
a load of carbonic acid, which it carries back to the lungs. 



RESPIRATION AND VOICE. 79 

The blood also brings other waste matter from the capilla- 
ries, some of which is discharged through the skin, and 
some through the kidneys. 

What amount of air is required by the lungs ? 

About twenty cubic inches of air pass in and out of the 
lungs every time we breathe. If we breathe eighteen times 
per minute, we use about three hundred and sixty cubic 
inches of air in that time. This is equivalent to thirteen 
cubic feet, or seventy-eight gallons, per hour ; and three 
hundred cubic feet, or about sixty barrels, per day. 

Describe the vocal cords. 

The vocal cords are elastic membranes stretched across the 
opening to the larynx and attached to the sides. When not 
in use they spread apart, leaving a narrow opening, through 
which the air passes into and out of the lungs, without pro- 
ducing voice. The changes in the position of these cords 
are made by the action of muscles, with which the larynx 
is provided. 

Hoio is sound produced by the vocal cords ? 

When we wish to use the vocal cords in producing sound, 
the muscles of the larynx contract and draw the cords tight 
across the opening. The air passing between the parallel 
edges of the cords, if the current is sufficiently strong, sets 
them vibrating, and thus sound is produced in the same way 
as by the rapid vibrations of the tongues of the accordion, 
or the strings of a violin. 

Hoiv are the tones of the voice changed by the vocal cords ? 

Sounds are varied chiefly by changing the length and ten- 
sion of the vocal cords. When high tones are to be produced 
the cords are made short, tight, and are drawn close together; 
low tones require the opposite conditions. The loudness 
of a tone depends upon the quantity of air, and the force 



80 BRIEF LESSONS ON THE HUMAN BODY. 

with which it is expelled from the lungs. The tones of the 
voice are also modified by the lips, tongue, and teeth. 

What is meant by " change of voice "? 

In early childhood the character of the voice is nearly the 
same in both sexes. About the age of fourteen, the vocal 
organs begin to enlarge rapidly. In a boy, the larynx becomes 
almost double its former size, and the voice " changes " and 
takes a masculine tone. In girls the larynx increases about 
one-third in size. The larynx of a woman is smaller than 
that of a man. During the period of change, especially 
with boys, muscular control of the organs is diminished, 
which produces an uncertainty of tones in singing or de- 
claiming. 

Why does a cold sometimes affect the voice ? 

The voice is often changed and sometimes destroyed by 
what is known as a cold. In such cases the muscles which 
control the vocal cords become so inflamed, or swollen, that 
they cannot be used. Hence such a person can only speak 
in a whisper. A whisper can be produced by the lips, tongue, 
and teeth, without the aid of the vocal cords. 

What actions are modifications of ordinary movements of 
respiration ? 

Coughing, sneezing, sighing, yawning, laughing, etc., are 
caused by a modification of the ordinary movements of 
respiration. A cough is a violent expiration in which the 
air is driven through the mouth, caused by some irritation 
of the air-passages. A sneeze is a similar act, except that 
the air is driven through the nose. A sigh is a prolonged 
inspiration, followed by an audible expiratiou. A yaivn is 
very much like a sigh. Laughing and crying are produced 
by short, rapid contractions of the diaphragm. 



CHAPTER XVI. 

HYGIEKE OF RESPIRATION. 

What can be said of the liability of the organs of respira- 
tion to disease ? 

On account of their constant use, their delicate structure, 
and their exposure to cold, dust, bad air, disease germs, 
etc., the lungs and air-passages are especially liable to dis- 
ease, and great care is necessary to keep them in health. 

Mention some things which should be observed in the care 
of the organs of respiration. 

In order to keep the organs of respiration in a healthy 
condition, we should breathe pure air, which requires well- 
ventilated rooms, and freedom from stagnant water and 
decaying animal or vegetable matter; the organs should not 
be compressed by tight clothing ; the pores of the skin 
should be kept open by proper attention to cleanliness ; 
breathing should be deep and full, so as to bring every part 
of the lungs into action, and should take place through 
the nose instead of the mouth ; extremes of heat and cold 
should be avoided ; alcohol and the excessive use of tobacco 
are sometimes a source of disease, and should likewise be 
avoided. 

Why is it necessary to breathe pure air f 

As we have already learned, pure air makes pure blood. 
And the health of all organs of the body is dependent upon 
pure blood. Air is made impure by carbonic acid and other 
6 



82 BKIEF LESSONS ON THE HUMAN BODY. 

matter, thrown out through the lungs and pores of the 
skin ; by the decay of animal and vegetable matter ; by dust 
floating in it ; by improperly-constructed or uncovered 
drain-pipes, sewers, etc. Impure air in all these forms 
should be avoided as far as possible. 

How does tight clothing interfere with respiration ? 

Tight clothing about the neck or chest prevents the free 
action of the lungs, and interferes with natural breathing. 
The practice of tight lacing presses upon the ribs so as 
to change the whole shape of the chest. The stomach 
and liver, as well as the lungs, are not given room to 
properly do their work. Tight clothing about the neck 
interferes with the action of the larynx, and is liable to 
bring on irritation which may end in bronchitis or con- 
sumption. 

How does cleanliness of the shin "benefit the organs of 
respiration ? 

The skin is one of the avenues through which impurities 
from the body are thrown off. If these impurities are 
allowed to accumulate upon the skin, they clog the pores, 
and prevent the escape of waste matter. Extra work then 
is required of the lungs and other organs, which they may 
not be able to do properly. Hence we may say that bathing 
keeps the pores open, promotes excretion, and aids in regu- 
lating bodily temperature, and in warding off colds, fevers, 
and other disorders. It is believed by many medical au- 
thorities that proper bathing will to a great extent prevent 
or cure catarrh and colds in throat or lungs. 

Why should we breathe deep and full ? Why should we 
breathe through the nose ? 

By full deep breathing the blood gets the benefit of more 
air, and is more thoroughly purified. The lungs, also, are 



HYGIENE OF RESPIRATION. 83 

made healthier and stronger by the exercise, and conse- 
quently less liable to disease. 

The reasons for breathing through the nostrils, instead of 
the mouth, have been given in answer to the same question 
on page 76. 

Why should extremes of heat and cold, or sudden changes 
of temperature, he avoided ? 

By the aid of clothing and artificial heating, man is able 
to endure a climate subject to wide ranges of temperature. 
Yet care should be taken to avoid exposure to extremes of 
temperature. The passing from an overheated room out 
into extreme cold air is liable to cause congestion of the 
lungs, or diseases of the throat. The living in overheated 
rooms during winter will make any person, child or adult, 
tender and delicate, and especially liable to disease from 
exposure to cold. Living-rooms, as far as possible, should 
be kept at a uniform temperature of about 68° or 70° F. 

In ivhat way does alcohol injuriously affect respiration ? 

It is said that so small a part of alcohol as one part to five 
hundred of the blood will materially check the absorption 
of oxygen in the lungs. Consequently, unable to take up 
oxygen, the blood retains its carbonic acid and goes back 
through the system with the poison which it ought to 
throw off. Alcohol in excess, also, tends to bring on inflam- 
mation of the lung-tissues, and hence lessens the breathing 
capacity. And there is good medical authority for saying 
that this action on lung-tissues often leads to a form of 
consumption known as "alcoholic consumption." 

What is the effect of tobacco upon the organs of respira- 
tion ? 

The smoking of tobacco, especially if carried to excess, 
has often caused diseases of the organs of respiration. The 



84 BRIEF LESSONS ON THE HUMAN BODY. 

strong, heated smoke irritates the mucous membrane of the 
mouth and throat, causing what is called "smoker's sore 
throat/' It also prevents the perfect oxidation of the blood 
and interferes with the assimilation of food. The smoking 
of cigarettes by boys is extremely injurious. The smoke of 
the paper is irritating to the lungs, the smoke is more 
directly inhaled, and the ingredients used in their manu- 
facture are often filthy and harmful. 

What is meant by malarial 

The word malaria means bad air. Hence malaria is a 
disease caused by breathing air poisoned by gases, or parti- 
cles of matter that arise from decaying animal or vegetable 
matter, from drain-pipes, marshes, etc. It is supposed that 
little atoms, called spores, rise into the air from these 
sources, and, entering the lungs, poison the blood, produc- 
ing the disorder from which so many people in some parts 
of the country suffer. 

Name some of the diseases of the organs of respiration. 

Among the diseases to which the organs of respiration 
are subject are : bronchitis (bron-kl'-tis), an inflammation 
of the bronchial tubes ; pleurisy, an inflammation of the 
pleura, or membranous covering of the lungs ; pneumonia, 
an inflammation of the lungs, chiefly affecting the air-cells; 
consumption, a disease which destroys the substance of the 
lungs ; asphyxia (as-fix'-i-a), suspended animation from suf- 
focation, drowning, etc. ; diphtheria, a peculiar sore throat, 
a contagious, often fatal, and much-dreaded disease ; croup, 
an inflammation of the mucous membrane of the larynx 
and trachea. 

NOTES AND SUGGESTIONS. 

Note 1. Structure of Lungs, etc. — In order to study the structure of 
the lungs, trachea, larynx, etc,, get from the market the lungs of a 



HYGIENE OF RESPIRATION. 85 

sheep or pig, with the trachea attached. See that none of its parts are 
mutilated in cutting. The lungs may be inflated by the use of a bel- 
lows. Show structure of trachea, larynx, and vocal cords. The lungs 
of animals are sometimes called lights. Place them on water, they will 
float. 

2. Experiments icith Oxygen and Carbonic Acid. — If the apparatus 
can be obtained, some interesting experiments can be made by showing 
the effects of oxygen and carbonic-acid gas on a burning candle, and 
also upon some small living animal as a mouse. A text-book on chem- 
istry will give directions for preparing and collecting these gases. 

3. Danger from too Much Oxygen. — The experiments mentioned 
above with oxygen would show the effects of an excess of oxygen in the 
air. It would become a very destructive agent ; the tissues of animals 
would be rapidly consumed, and all substances capable of being set on 
fire would burn beyond control. In pure oxygen steel would burn, as 
may be shown by burning a watch-spring in a jar of oxygen. 

4. Show Carbonic Acid and Watery Vapor in the Breath. — The test of 
carbonic acid is lime-water. Carbonic acid will form with lime-water a 
milky precipitate of carbonate of lime. Take a glass tumbler with a 
little lime-water in it, and breathe, or blow the breath into it, through 
a glass tube. The lime-water will turn milky, and if allowed to stand 
the white carbonate will settle to the bottom. 

Water vapor, or moisture, in the breath may be shown by breathing 
against cold glass or steel. The moisture will be condensed on the 
surface. 

5. How Some Animals Breathe. — It will be of interest to notice the 
organs of respiration in some animals ; for instance, the frog, fish, 
whale. Do plants breathe ? How ? 

6. Black Hole of Calcutta. — During the English war in India, one 
hundred and forty-six English prisoners were shut in a room scarcely 
large enough to hold them. There were two small windows, both on 
the same side of the room, through which air could enter. At the end 
of eight hours only twenty-three were alive, and they were in a deplor- 
able condition, from want of air. 



CHAPTER XVII. 

ORGANS OF MOTION. — MUSCLES. 

What are the muscles ? 

The muscles are the organs by which the movements of 
the body are performed. They are the deep-red flesh of the 
body, or as it is called in animals, " lean meat." The num- 
ber of muscles is about five hundred. 

What are the uses of the muscles ? 

The uses of the muscles are, to give the body the power 
of motion, to help hold the bones in position, and, together 
with the fat, to fill out the body and give it a symmetrical 
form. They also shield the blood-vessels ; diminish the 
force of shocks and blows ; and in connection with the bones 
enclose the cavities of the chest, abdomen, and pelvis. 

Describe the structure of muscles. 

The muscles are made up of fibres, held together by a 
delicate tissue, called connective tissue. These fibres, if 
examined under the microscope, appear to be composed of 
still finer fibres, called fibrils. In shape and in length, mus- 
cles vary greatly. Some are round ; others are flat, square, 
or triangular. In length, they vary from one-eighth of an 
inch to nearly three feet. Muscles are large and thick in 
the middle and small at the ends. The middle part is called 
the body, or swell, of the muscles, and possesses the power 
of contraction. 

How do muscles produce motion ? 



ORGANS OF MOTION. — MUSCLES. 



87 




The Muscles. 



88 BRIEF LESSONS OK THE HUMAN BODY. 

All the varied and wonderful movements of the body, 
made in walking, working, talking, breathing, the beating 
of the heart, etc., are made by the contraction of muscles. 
That is, the muscles shorten themselves, and bring their 
two ends nearer together. In this way the bones to which 
they are attached are moved. Every muscle is provided 
with nerves which connect it with the brain, and through 
these nerves it receives the stimulus, or the nerve-force, 
which gives it the power to act. After a muscle has become 
shortened, it will remain so for only a short time. It soon 
becomes tired and begins to relax. 

Hoiv are muscles mostly arranged ? 

Muscles are, for the most part, arranged in pairs, or cor- 
responding sets, so that when motion is produced in one 
direction by one set, another set or group of muscles brings 
the limb back to its place again. The muscle which bends 
a joint is called a flexor muscle ; a muscle which brings a 
joint back to its place is called an extensor muscle. 

According to the control which the ivill has over muscles, 
how are muscles classified? 

According as they are, or are not, under control of the 
will, muscles are divided into two classes, voluntary mus- 
cles and involuntary muscles. Voluntary muscles are those 
which are under control of the will ; such as the muscles 
of the hands, arms, legs, trunk, face, etc. Involuntary 
muscles are those which are not under the control of the 
will ; the muscles of the heart and stomach are involuntary 
muscles. 

What are tendons, or sinews ? What is their use ? 

Tendons, or sinews, are strong, white, inelastic cords, 
which connect the muscles with the bones. Tendons are 
easilv felt on the inside of the wrist. Children often amuse 



ORGANS OF MOTION. — MUSCLES. 89 

themselves by taking the leg cut from a fowl, and moving 
the foot by pulling the tendons. The largest tendon of the 
body is in the heel, called the tendon of Achilles. 

The use of tendons is to give strength and freedom of 
motion, and at the same time place the moving muscles 
far enough away to prevent clumsiness. For example, the 
muscles which open and close the hand are situated in the 
forearm toward the elbow, and* tendons extend from them 
through the wrist to the fingers. It is easy to see how awk- 
ward, clumsy, and inconvenient it would be if, instead, the 
muscles were placed upon the wrist, or the fingers them- 
selves. 

Of what use is "fat" to the body? 

Fat usually constitutes about one-twentieth part of the 
weight of the body. It is situated about the internal organs, 
between the muscles, under the skin, and about the joints 
of the body. It acts as cushions to the various structures ; 
it helps to maintain an even temperature in the body ; it fills 
up inequalities, and so improves the symmetry of form ; it 
also serves for nutrition in time of need, especially in ema- 
ciating diseases or starvation. 



CHAPTER XVIII. 

HYGIENE OF MUSCLES. 

Name some things to be observed in the care of the 
muscles. 

The health of the muscles requires that the muscles 
receive a proper amount of exercise. This exercise should 
be regular, should not be too violent, nor should it be 
continued too long. The muscles should have rest after 
exhaustive strain or long-continued exercise. They should 
be abundantly supplied with pure blood, which requires 
proper food/pure air, and freedom from compression. They 
should not be weakened by the use of alcohol. 

Hoiv is exercise of muscles beneficial ? 

The beneficial effects of exercise upon the muscles are 
very marked. By use the muscles become larger, stronger, 
and more compact. By disuse they become smaller, soft, and 
weak. Such exercise, however, not only benefits the mus- 
cles themselves, but the good effects are shared by all the 
other organs of the body. The circulation of the blood is 
more vigorous, the temperature of the body rises, the brain 
becomes invigorated, the appetite and power of digestion 
are increased, the skin and lungs do their work more thor- 
oughly, and the whole body thrives under its influence. 

How may muscular exercise be injurious to the body? 

Exercise is good while it stimulates nature to build up 
the tissues. If the exercise is too violent, or too long-con- 



HYGIENE OF MUSCLES. 91 

tinued, it is injurious, because it tears down, or wears out, 
faster than nature can build up. Besides, muscles may be 
strained or ruptured, and blood-vessels burst by violent 
exertion. Useless feats of strength and endurance should 
be avoided. 

When is the best time for exercise? Name some varieties 
of exercise tvhich are beneficial. 

The best time to take exercise is, perhaps, about two 
hours after a meal. It certainly should not be taken just 
before or immediately after a meal, unless the meal or the 
exercise be very light. Among the varieties of exercise 
which are beneficial are : 1st, those that, as nearly as possi- 
ble, bring into equal action all the muscles of the body, as 
swimming, horseback riding, base and foot ball, lawn ten- 
nis, etc.; 2d, those that exert the muscles of the upper 
part of the body, as rowing, bowling, billiards, etc.; 3d, 
those that serve principally to develop the muscles of the 
lower part of the body, as walking, skating, dancing, bicy- 
cle riding, etc. 

Why should rest be taken after continued muscular 
exercise ? 

A period of repose should follow a period of muscular 
exertion, in order that new material may be brought to the 
muscles by the blood to replace that worn out by the exer- 
cise. Sore muscles and stiff joints will often be avoided 
if the exercise is made to cease gradually, not all at once. 
As repair goes on faster during sleep, we may say that 
sleep is the best means of restoring vigor to tired muscles. 

How do healthy muscles depend upon good blood ? 

The muscles depend upon the blood, not only for the 
materials necessary to their growth and nourishment, but 
for the removal of waste matter which, if allowed to 



92 BRIEF LESSOKS OK THE HUMAN BODY. 

remain, would poison, and so cause disease of the muscles. 
Both of these things require pure blood, and, as we have 
already learned, pure blood demands good food and pure 
air. Moreover, no article of dress should be worn which is 
tight enough to prevent the free flow of blood to any mus- 
cle, as it will interfere with its nourishment. 

What is the effect of alcoholic drinks upon the muscles ? 

Indulgence in beer, wine, or liquors containing alcohol, 
never does any good and often does harm. The injury 
may be direct or indirect. Careful experiments have been 
made which show that when spirits are used the muscles 
will not act with as much power, nor for as long a time, as 
when they are not used. Continued use of alcoholic drinks 
causes a change in the structure of the muscles. The con- 
nective tissue and fat in them become too abundant, and 
take the place of proper muscular substance. The stagger- 
ing of the drunkard shows that his muscles are not under 
good control. This probably is due to the fact that the 
nerves which govern these muscles are partially paralyzed. 
Mechanical work requiring great skill cannot be well done 
by a man addicted to the use of alcoholic stimulants. Indi- 
rectly the injury to muscles is due to weakened will, im- 
paired digestion, enfeebled heart, or disease of organs whose 
office it is to carry waste matters away from the body. 

Mention some diseases of the muscles. 

St. Vitus' Dance is a disease of the voluntary muscles, in 
which the muscles have an irregular and spasmodic motion 
beyond the control of the will. Convulsions are an invol- 
untary contraction of the muscles ; consciousness is want- 
ing, and the limbs are either rigid or in spasmodic action. 
Locked-jaw is a disease characterized by contraction of 
muscles, accompanied by spasms. It usually begins in the 



HYGIENE OF MUSCLES. 93 

lower jaw. A slight injury or wound is sometimes the 
cause. Rheumatism is a disease which affects mainly the 
connective, white, and fibrous tissues of the larger joints. 
There are two forms, called chronic and acute. The former 
is of long continuance; the latter terminates more speedily. 

NOTES AND SUGGESTIONS. 

Note 1. Show the Structure of Muscles. — The gross structure of mus- 
cle may be shown by examining a piece of well- boiled corned-beef. 
Put the beef on a firm table, and pick it to pieces with two darnings 
needles. Notice the connective tissue and the larger muscular fibres. 
When the fibres become too small to manage without, use a magnify - 
ing-glass. The small fibres may be examined with a microscope. 

The form and structure of muscles can also be readily shown in the 
hind-leg of a frog. Kill the frog by putting him in a covered jar con- 
taining a pint of water to which a little ether has been added. Remove 
the skin from the hind-leg. Notice the muscles between the knee and 
ankle joints, also the tendons running to the toes. The nerve of this 
muscle may be seen, as a slender white thread, entering the muscle just 
below the knee. 

2. Name and Locate Some Important Muscles. — Pupils should be 
taught to name and locate some of the most important muscles of 
the body. This can be done by reference to the cuts in some text-book, 
or on some chart. They should also be able as far as possible to point 
them out on their own persons, and to tell the office of each. 

3. Shoiv Tendons. — The leg of a chicken or turkey affords an excellent 
opportunity for examining tendons. The muscles which move the toes 
are in that part of the leg known as the " drumstick." After the lower- 
leg has been cut off, by pulling some of the tendons the toes are closed, 
by pulling others they are opened. 

4. Tendon of Achilles. — This tendon was so named because, as the 
story goes in fable, when Achilles was an infant his mother held him 
by the heel while she dipped him in the River Styx, the waters of 
which had the power of rendering any one invulnerable to weapons. 
His heel did not get wet, and was, therefore, his weak point, to which 
Paris aimed the fatal arrow, 



94 BRIEF LESSONS ON THE HUMAN BODY. 

5. Animals that Hibernate. — Some animals, the common tortoise for 
instance, burrow themselves in the earth in the latter part of autumn, 
and do not reappear until the opening of spring. Some species of bears 
become very fat through the summer and fall, but pass the winter in a 
cave or holiow tree in a state of inactivity, eating no food, so far as is 
known. The fat, stored up during the summer and autumn, keeps the 
body warm, and supplies the little nourishment which such a state of 
inactivity requires. In the spring they come out of their hiding-places 
lank and hungry. 

6. Strength of Insects. — Insects, when their size is taken into con- 
sideration, present some remarkable examples of muscular strength. A 
flea harnessed will draw seventy or eighty times its own weight. A 
horse can draw about six times his weight. A flea can jump several 
feet at a leap. A common beetle weighing fifteen grains has been 
known to carry on his back 4,759 grains, or nearly 320 times his own 
weight. 



CHAPTER XIX. 

THE NERVOUS SYSTEM. 

What is the office of the nervous system ? 

The office of the nervous system is to give the body intel- 
ligence, sensation (five senses), and the power of motion. 
By intelligence we mean all the higher powers of mind by 
which man is distinguished from the lower animals ; sensa- 
tion includes feeling, seeing, hearing, tasting, and smelling ; 
power of motion may include all the involuntary motions of 
the vital organs, heart, lungs, stomach, etc., as well as those 
made by authority of the will, for all muscles, voluntary 
and involuntary, depend upon the nervous system for their 
stimulus to action. 

Name the organs of the nervous system. 

The organs of the nervous system are the brain, spinal 
cord, and nerves. 

What is meant by nerve-tissue ? 

Nerve-tissue is the soft, marrow-like substance of which 
the principal bulk of the brain, spinal cord, and nerves is 
formed. 

What are nerves f 

Nerves are simply portions of the brain and spinal cord, 
which extend to every part of the body. When seen by the 
naked eye, a nerve looks like a silvery-white cord. With a 
microscope it is seen to consist of a bundle of delicate little 
fibres. 

Describe the location, size, and shape of the brain. 



96 



BRIEF LESSORS ON THE HUMAN BODY. 




A Representation of the Brain, Spinal Cord, and Spinal Nerves. 
1, the cerebrum. I 3, 3, spinal cord. 

8, the cerebellum. | 4, the sciatic nerve, 



THE NERVOUS SYSTEM. 97 

The brain is the principal organ of the nervous system. 
It occupies the entire cavity of the skull, and consists of 
several separate masses of nerve-tissue abundantly supplied 
with blood-vessels. In shape it is oval, with one extremity 
larger than the other. The average weight of the brain is 
about fifty ounces, or a little more than three pounds. 

Name the three "principal masses which compose the brain. 

The three principal masses which compose the brain are 
the cerebrum, or brain proper ; the cerebellum, or lesser 
brain ; and the medulla oblongata. 

Of ivhat two kinds of matter is the substance of the brain 
composed ? 

The substance of the brain is composed of two kinds of 
matter, — gray matter and white matter. The outside of 
the brain is formed of the gray matter, and the inside of 
the white matter. It is supposed that the gray matter is 
the generator of nerve-force, and that the white matter is 
the conductor of nerve-force. What nerve-force is we do 
not know. It is like electricity in some respects, in others 
quite unlike it. 

Name the membranes which envelop the brain. 

Within the skull the brain is enveloped in three mem- 
branes, or coverings. They are called dura mater (tough 
covering), the arachnoid (spider's web), andpia mater (soft 
covering). The office of the dura mater is to protect the 
brain and to assist in keeping it together. The arachnoid 
secretes a lubricating fluid which moistens the surface of 
the brain. The pia mater contains blood-vessels which help 
to supply the brain with blood. 

Describe the cerebrum, or brain proper. 

The cerebrum is that part of the brain which fills the entire 
upper part of the skull. Its surface has a peculiar wrinkled, 
7 



98 BRIEF LESSONS ON THE HUMAN BODY. 

or folded-up, appearance ; and it is divided into two parts, 
or halves, by a deep cleft which extends from front to back. 
Looking at the cerebrum from the top its appearance is not 
unlike that of the meat of an English walnut. The cere- 
brum is believed to be the chief organ of the mind, the 
seat of intelligence and of intellectual processes. 

Describe the cerebellum. 

The cerebellum, or little brain, is less than one-eighth 
the size of the cerebrum. It is situated directly under the 
back part of the cerebrum, and is also divided into hemi- 
spheres, and is composed of gray and white matter. It is 
believed that this part of the brain is the regulator of mus- 
cular action. 

Describe the medulla oblongata. 

The name, medulla oblongata, means "oblong pith, or 
marrow." This part of the brain is the enlarged upper part 
of the spinal cord, and forms the connection between the 
cerebellum and the spinal cord. It is only about an inch 
and a half long, but it is an important part of the brain. 
It is believed that the medulla oblongata is the seat of 
sensation, and that it has control of the action of the heart 
and lungs. It is probably the most sensitive portion of the 
body, a slight injury causing death. 

Describe the spinal cord. 

The spinal cord is an extension of the substance of the 
brain, and extends downward through the cavity of the 
backbone. Like the brain, it consists of two kinds of mat- 
ter, gray and white, but the gray matter is en the inside 
and the white outside. Between the bones of the spine, the 
spinal cord sends out to various parts of the body branches 
called spinal nerves. From one set of these branches, the 
spinal cord receives impressions from various parts of the 



THE NERVOUS SYSTEM. 99 

body and carries them to the brain ; through another set, 
it sends out the commands of the brain to the voluntary 
muscles. 

From their origin, how are nerves classified ? 

From their origin, or place from whence they start, nerves 
are classified as cranial nerves and spinal nerves. The cra- 
nial nerves start from the base of the brain, within the 
skull, or cranium. They consist of twelve pairs, and extend 
to the eye, ear, tongue, nose, throat, stomach, heart, etc. 
The spinal nerves, as has already been said, are branches 
of the spinal cord. They consist of thirty-one pairs, and 
extend to the arms, chest, abdomen, legs, etc. 

A ccording to office, hoiv are nerves classified ? 

From their office, nerves are classified as sensory nerves 
and motor nerves. The sensory nerves are those which carry 
impressions received through the organs of sense, hearing, 
sight, touch, taste, etc., from the outside of the body to the 
brain. The motor nerves are nerves connected with the 
muscles. They carry the commands of the brain to the 
muscles, so that the muscles move whenever the brain wills 
them to. 

To what may the nervous system be compared ? 

The nervous system may be compared to a telegraphic 
system. The brain is the central office, from which mes- 
sages are sent back and forth over the nerves, which corre- 
spond to the wires. If a nerve, or a wire, leading to any 
part be severed, communication with that part instantly 
ceases. 



CHAPTER XX. 

HYGIEKE OF THE KEKVOUS SYSTEM. 

What may be said regarding the liability to disease of the 
nervous system ? 

Although the nervous system is so delicate in its structure 
and so mysterious in its work, it is not in itself especially 
liable to disease. But it is so closely connected with other 
parts of the body that anything which injures them is liable 
to injure it. The man whose muscles and digestive, cir- 
culatory and respiratory organs are in a healthy condition/ 
usually possesses a healthy nervous system and a vigorous 
mind. The health of these organs has been quite fully dis- 
cussed in other chapters, so that little need be repeated 
here. Something more might be well said, perhaps, regard- 
ing the need of sleep, exercise, rest, recreation, and the 
effects of alcohol and tobacco. 

What may be said regarding the effects of sleep on the 
nervous system ? 

The tissues of the nervous system, like those of other 
organs, depend upon the blood for the materials of growth 
and repair. Action on the part of the nervous system 
destroys, or wears out, nerve-tissue. Every thought, sensa- 
tion, or effort of the will which goes out from the brain 
consumes a part of its substance. Consequently there must 
be periods when the brain must stop work for repairs. 
Whenever we are awake the brain is more or less active. 



HYGIENE OF THE NERVOUS SYSTEM. 101 

Sleep is the only period of complete rest for growth and 
repair. The amount of sleep necessary will depend upon 
age, health, occupation, and natural temperament of the 
individual ; but sound sleep, and plenty of it, is one great 
condition necessary to a healthy nervous system. 

How does exercise benefit the nervous system ? 

Physical exercise has already been shown to be beneficial 
to all organs, because it promotes healthy action and a 
more vigorous circulation of the blood ; but regular and sys- 
tematic mental exercise is essential to the health of nerve- 
tissue. Idle minds, like idle muscles, become weak. Cul- 
tivation and systematic exercise quicken the action of the 
brain, and also give it the power of sustaining action for 
a longer period of time. Mental exercise should also be 
adapted to the age and health of the individual. Parents 
and ambitious teachers should see to it that young minds 
are not overworked. 

Why does the drain need rest and recreation ? 

The confining of the mind for a long time to one subject 
of thought is exhausting. In order to keep the powers of 
the brain vigorous and lasting, the lines of mental work 
should be occasionally changed, and in this way the brain 
obtains rest. Every one is benefited by a vacation, or a 
change of employment, in which the ordinary routine of 
every-day life is broken up. This applies to business men, 
students, farmers, and mechanics alike. 

What are some of the abuses of the nervous system ? 

The nervous system is sometimes abused by overwork, but 
fretting and worry are more fruitful causes of mental dis- 
order. Pupils fret and worry about examinations and pro- 
motions, and become peevish and nervous, and lay the 
foundations of future ill-health. Older persons worry them- 



102 BRIEF LESSORS ON THE HUMAN BODY. 

selves into nervous prostration over business cares and the 
struggle for wealth and position. The nervous system is 
frequently abused by the use of drugs and medicines for 
producing sleep, or deadening pain. The disturbance to the 
nervous system is more than enough to counterbalance all 
good results. The use of laudanum, morphine, chloroform, 
for such purposes, except by the advice of a physician, 
is dangerous. The dose must be constantly increased in 
order to produce the same effects, and frequently the user 
is unconsciously led into a terrible and fatal bondage. The 
injury done to helpless infants by the careless use of "sooth- 
ing-syrups " and the like is pitiful. An overdose is liable to 
be fatal, and at best they paralyze the nerves, interfere with 
digestion, and poison the blood. The use of alcohol and 
tobacco has, in some respects, a similar effect. 

Hoio does alcohol affect the nervous system ? 

The injurious effects of alcohol upon the nervous system 
are more marked than upon any other organs of the body. 
It injures the substance of the brain and impairs the thought- 
producing power. It sometimes collects in the brain, caus- 
ing paralysis and death. It destroys a man's judgment and 
his will-power, leading him to do deeds of crime and vio- 
lence, and rendering him an utter slave to his animal nature. 
Its excessive use leads to insanity and to a terrible form of 
delirium, known as delirium tremens. 

This question will be more fully answered in a special 
chapter on Stimulants and Narcotics. 

WJiat is the effect of tobacco on the nervous system ? 

The use of tobacco has a peculiarly injurious effect upon 
young and growing persons. And adults are by no means 
exempt from harm, although, if used by them in modera- 
tion, it may apparently do no harm except as small doses 



NOTES AND SUGGESTIONS. 103 

of any narcotic ma)' do harm. In excessive quantities, its 
harmful action to old or young is marked. It deranges 
the working of the brain and nerves so that ideas lack clear- 
ness, will-power becomes weakened, memory impaired, and 
the nerves deprived of the power to steadily control the mus- 
cles. Its habitual use is foolish, costly, and ill-becoming, 
and is a thing to be avoided by a young man who wishes 
to succeed in life and to keep a constitution strong and 
vigorous. 

NOTES AND SUGGESTIONS. 

Note 1. Difficult to Dissect the Brain of an Animal. — It is a diffi- 
cult matter to dissect the brain and spinal cord of an animal, and, 
unless skilfully done, the attempt to do it before a class will be of little 
value. If skilfully performed the operation can be made a valua- 
ble object-lesson. To show the brain, a sheep's or calf's head may be 
obtained from the butcher. The spinal cord can be better shown by 
dissecting the body of a cat or rabbit. The cutting of bones can be 
mostly done with strong short-bladed shears. Great patience is 
needed to make such dissections successful. 

2. Nervous System Belongs to Animals Only. — Organs of circula- 
tion, digestion, and respiration belong in modified forms to the vegeta- 
ble kingdom, as well as to the animal ; while a nervous system, so far 
as is known, belongs to animals only, and the extent of its development 
determines the position in the scale of intelligence to which the various 
animals belong. The average weight of the human brain in propor- 
tion to that of the entire body is about 1 to 36. The average in mam- 
mals is 1 to 186, 

3. Large Brains. — There have been few men of distinguished ability 
whose brains have been small. As a rule, the size of the brain is an 
index of mental development. The following are the brain weights of 
some distinguished men: Cuvier, 64.5 oz. ; Daniel Webster, 53.5 oz. ; 
Abercrombie, 63 oz. ; Agassiz, 53.4 oz. 

4. Speed of Thought. — The rate of motion with which a message 
travels along a nerve to or from the brain, is thought to be about two 
hundred feet per second. The estimate has been reached by experi- 



104 BRIEF LESSONS ON THE HUMAN BODY. 

ments upon lower animals. It is slower than electricity, but consider- 
ing the short distance which such messages travel it is practically 
instantaneous. 

5. Pain Felt in a Limb after Amputation. — For a long time 
after a limb has been amputated, pain will be felt in it as if it still 
formed a part of the body. The explanation is this : Pain, strictly 
speaking, is in the mind, not in the various parts of the body. The 
mind only can feel ; hence when any nerve brings into the brain the 
news of an injury, the brain at once refers the pain to that part of the 
body where the nerve terminated. So in the case of injury to the stump 
of an amputated limb, the mind refers the pain to the point to which 
the nerve formerly led. 

6. Peculiarities of the Brain. — In appearance the brain is the least 
solid and the most unsubstantial looking organ in the body. Eighty 
percent, of its substance is water, nine per cent, is albumen, and the 
rest fat and small quantities of a few other substances. While the 
brain is the seat of all sensation, it has no sensation. The spinal cord 
and every nerve is sensitive to the slightest touch, but the brain may be 
injured, even cut or burned, without pain. 



CHAPTER XXL 

THE SKIN, AND ORGANS OF SPECIAL SENSE. 

What are the offices of the skin ? 

The offices of the skin are quite varied. It makes a 
covering and a protection for the outer surface of the body ; 
it is an organ of feeling ; it helps to provide the means of 
escape for waste matter ; it is a regulator of temperature ; 
and it is an organ of absorption. The skin is an organ of 
more importance than most people believe it to be. 

Describe the structure of the skin. 

The skin consists of two distinct layers. The inner 
layer is called the dermis, or true skin ; the outer one, the 
cuticle, or scarf skin. The inner layer is also sometimes 
called the cutis, and the outer one the epidermis. These 
two layers are closely united, but they may be separated. 
This separation takes place whenever a blister is formed ; 
the epidermis, or cuticle, is lifted up from the dermis, or 
true skin, and a watery fluid collects between. 

Describe the cuticle, or scarf shin. 

The cuticle in most parts of the body is thinner than the 
true skin ; it is tough, elastic, without feeling, and does not 
bleed when cut ; it is composed of minute flat cells arranged 
one upon another in layers. The' outer layers of these cells, 
on account of exposure to atmosphere, friction, etc., become 
hard, and being constantly worn out fall from the body in 
the form of very fine scales. In the scalp these scales are 



106 BRIEF LESSONS ON THE HUMAN BODY. 

called "dandruff." As fast as they wear out and fall off, 
they are renewed from beneath. The material out of which 
the new cells are formed is supplied by the blood-vessels 
which lie in the true skin. 

Describe the dermis, or true shin. 

The dermis, or true skin, lies beneath the cuticle. It is 
firm, elastic, sensitive, and well supplied with blood-vessels. 
The outer surface of the true skin rises into little ridges 
called "papillae/' into which capillaries and nerves are dis- 
tributed. These papillae are most numerous where the sense 
of touch is most acute, as on the tips of the fingers. The 
true skin contains the sweat and oil-glands, nerves, and 
hair follicles (little sacs, or pouches). 

Of what use are the sweat-glands ? 

The sweat-glands consist of very fine tubes, coiled up 
into knots, from each of which a little duct, or pore, extends 
to the surface of the skin. These glands gather up from 
the blood in the capillaries perspiration and waste matter, 
which passes out through the pores to the surface of the 
body. This work is going on at all times, but the amount 
of perspiration varies greatly at different times. Anything 
which tends to heat the body causes it to flow more freely. 
If the moisture dries up so as not to show itself upon the 
skin, it is called insensible perspiration. When it is poured 
out faster than it evaporates, and collects in little drops on 
the surface of the skin, it is called sensible perspiration. 
It is said that there are about two and a half millions of 
sweat-glands in the surface of the body. The average 
amount of perspiration per day is about two pints, about 
two per cent, of which is solid matter. The use of per- 
spiration, besides taking water and worn-out matter from 
the blood, is to regulate the temperature of the body. 



THE SKIN, AND ORGANS OF SPECIAL SENSE. 107 

That is to say, evaporation diminishes temperature. When 
this moisture comes to the surface it evaporates ; the heat 
which changes it into vapor is taken from the body, which 
makes the body cooler. 

Describe the oil-glands. Of what use are they ? 

The oil-glands are little glands which pour an oily fluid 
into the sides of the pits in which the roots of hairs are 
contained. This oily fluid keeps the hair glossy and the 
skin soft. It also keeps the skin from absorbing water or 
other substances too rapidly, and from drying up too fast 
on a hot dry day. 

To ivhat is the complexion, or color of the skin, due ? 

In the cells on the under side of the cuticle little grains 
of pigment, or coloring matter, are found. The varying 
tint of this coloring matter in different persons makes the 
difference in complexion between the blonde and brunette, 
the European and the African. The action of the sun on 
this coloring causes " tan " and freckles. 

Wliat are hair and nails, and how do they grow ? What 
are their uses ? 

The hair and nails are modified forms of the cuticle. 
They both grow by the addition of new cells at their roots, 
or lower ends. Hair is found on nearly all parts of the 
body except the palms of the hands and soles of the feet. 
Its chief use is to protect the body from excessive heat and 
cold. The nails provide a kind of armor to protect the 
ends of the fingers and toes, which are liable to injury. 



CHAPTER XXII. 

THE SKIN, AND ORGANS OF SPECIAL SENSE. — CONTINUED. 

How many special senses have toe, and what are they ? 

It is said that there are five ways by which the brain may 
receive impressions from objects outside of the body ; that 
is, five gateways of knowledge, called the five senses, — 
touch, taste, smell, hearing, and sight. 

Describe the sense of touch and feeling. 

The skin is the chief organ of the sense of feeling, in 
which many sensory nerves have their extremities. The 
impressions received from touch, heat and cold, and pain, 
are transmitted from the skin through these nerves to the 
brain; and the brain locates, with more or less accuracy, 
the part of the skin from which the impressions come. 
The sense of touch is most delicate on the tip of the tongue, 
the edges of the lips, and the ends of the fingers. It is 
least delicate in the middle of the back. 

Describe the sense of taste. 

The sense of taste is located in the mucous membrane on 
the upper side of the tongue and the under side of the soft 
palate. On these membranes there are innumerable eleva- 
tions, or papillae, containing the endings of nerve-fibres. 
Dissolved particles of substances tasted come in contact 
with these nerve-fibres, and the impression is carried to the 
brain. The use of taste was originally, perhaps, to guide 
in the selection of food, but force of habit and highly 



THE SKIN, AND ORGANS OF SPECIAL SENSE. 109 

seasoned foods have greatly impaired its use for this pur- 
pose. 

Describe the sense of smell. 

The sense of smell is very closely connected with that of 
taste, and we often fail to distinguish between them. The 
sense of smell has its location in the mucous membrane 
which lines the upper portion of the cavities of the nostrils. 
The olfactorv nerves are distributed over the surface of this 




The Ear. 

membrane, where particles of matter which produce odors 
come in contact with them, and they transmit the impres- 
sion to the brain. The uses of the sense of smell are to 
guide us in the selection of food, and to give us warning 
against bad air. 

Describe the ear, or organ of hearing. 

The ear, or organ of hearing, consists of three parts — the 
external ear, the middle ear or tympanum (drum), and the 



110 BEIEF LESSONS ON THE HUMAN BODY. 

internal ear or labyrinth. The external ear consists of car- 
tilage, curiously folded for catching sound. Leading inward 
is the auditory canal about an inch long, across the lower 
end of which is stretched the membrane of the tympanum, 
which is kept moist and soft by a fluid wax called ear-wax. 
The tympanum, or middle ear, consists of a cavity filled 
with air, and communicating with the throat by a small 
tube called the Eustachian tube. Across this cavity, from 
the membrane of the tympanum to the inner ear, hangs a 
chain of three curious little bones, called from their shape 
the hammer, the anvil, and the stirrup. The internal ear, 
or labyrinth, consists of winding passages in solid bone. 
Spread over these passages, like a lining, is the auditory 
nerve, and a watery liquid fills the remaining space. The 
auditory nerve extends from this part of the ear to the 
brain. 

Explain how tve hear. 

All things which produce sound vibrate in so doing, and 
these vibrations are communicated to the air around them. 
The vibrating air strikes against the membrane of the tym- 
panum, and the vibrations are forwarded to the inner ear, 
partly by the air in the middle ear and partly by the chain 
of little bones. In this way the motion is communicated 
to the liquids in the labyrinth, which in turn excite the 
ends of the auditory nerve. The auditory nerve conveys 
the impression to the brain, and the sensation of sound is 
the result. 

Describe the position, shape, and size of the eye, or organ 
of sight. 

The eye is situated in the upper part of the front of the 
skull, protected by the surrounding bones. The eyeball, 
which is about an inch in diameter and nearly spherical, 



THE SKIN, AND ORGANS OF SPECIAL SENSE. Ill 



rests in a soft elastic bed of fat, which supports and pro- 
tects it, and at the same time allows it to move freely in 
all directions. 




A Vertical Section through the Middle of the Eyeball. 



1, cornea. 

2, aqueous humor. 

3, pupil. 

4, iris 

5, lens. 

6, ciliary processes. 

7, canal around the lens. 

8, sclerotic coat. 



9, choroid. 

10, retina. 

11, vitreous humor. 

12, optic nerve. 

13, 14, 15, muscles of the eyeball 
and of the eyelid. 

16, 17, eyelids. 



Describe the coatings of the eyeball. 

The walls of the eyeball consist of three distinct coats or 
coverings, — the sclerotic, the choroid, and the retina. The 
sclerotic is the outer covering, and is generally called the 
" white of the eye." It is tough and strong so as to pro- 



112 BRIEF LESSONS ON" THE HUMAN BODY. 

tect arid to keep in shape the delicate structures within, 
and to afford an attachment foj; the muscles which move 
the eye. It has an opening in front in which a round 
transparent plate, or window, called the cornea, is placed. 
The choroid coat is immediately under the sclerotic. It is 
much more delicate in structure, and contains nerves and 
blood-vessels. It is lined with a coating of black pigment 
which serves to keep out the unnecessary rays of light. 
The front part of this coat is a movable curtain, called the 
iris, in the centre of which is the opening called the pupil. 
The color of the choroid as seen in the iris gives the color 
to the eye — as black, blue, gray, etc. The iris is provided 
with muscular fibres which enable it to move so as to 
enlarge or contract the pupil for the purpose of admitting 
more or less light. The retina is the innermost coat of the 
eyeball. It is a delicate transparent film, and lines only 
the rear half of the eyeball. It is the immediate seat of 
sight, and is really an extension and an expansion of the 
optic nerve. 

Of ivhat is the interior of the eyeball composed ? 

The interior of the eyeball is filled with transparent 
liquid or jelly-like matters, called humors. These liquids, 
or humors, are three in number, — the crystalline lens, just 
behind the iris ; the aqueous (watery) humor, between the 
crystalline lens and the cornea; and the vitreous (glassy) 
humor, behind the. crystalline lens and filling the entire 
back part of the cavity of the eyeball. 

What are the uses of the humors of the eye ? 

The humors of the eye fill up the cavities of the eyeball, 
and keep the different parts in position and at proper dis- 
tances from each other. They also receive the rays of light 
which enter the eye, and so bend and direct them that all 



THE SKIN, AND ORGANS OF SPECIAL SENSE. 113 

rays which start from one point outside of the eye are 
brought to a focus, or to one point again, on the retina. 
This, especially, is the work of the crystalline lens. An 
exact picture of the thing looked at is thus formed on the 
delicate retina in the back part of the eye. The impression 
received is carried to the brain through the optic nerve, and 
the sensation of sight is produced. 

Of what use are tears ? 

Tears are a special fluid provided by nature for the pro- 
tection of the eyes. They keep the surface of the eye clean 
and moist. The lachrymal glands, or tear-glands, are situ- 
ated in the upper and outer sockets of the eyes, just above 
the balls. The tears after passing over the eyeball finally 
find their way to the inner corner of the eye, and there 
enter little openings which lead to the nostrils, whose inner 
surfaces they moisten. 



CHAPTER XXIII. 

HYGIENE OF SKIN AND ORGANS OF SPECIAL SENSE. 

Name some things to he observed in the care of the shin. 

The skin should be kept at a proper temperature by suita- 
ble clothing ; it should be kept clean by frequent bathing ; 
its healthy action should not be interfered with by the use 
of cosmetics and hair-dyes. 

How does proper clothing serve to keep the shin in a 
healthy condition ? 

Proper clothing serves to keep the skin in a healthy condi- 
tion by keeping it at an even temperature. It is our defence 
against the frequent changes of weather in our fitful cli- 
mate. If clothing is insufficient, the skin is liable to become 
chilled, perspiration to be checked, and a " cold "is the 
result. Clothing should be adapted to the climate and the 
season of the year. There is more danger from too little 
than from too much clothing. Many children die every 
year from lung-diseases because of insufficient clothing. 

Why should the shin be bathed frequently ? 

Prequent bathing is necessary in order to keep the pores 
of the skin open, and also to remove impurities which, if left 
on the skin, might be absorbed and carried back to poison 
the blood. Bathing not only cleanses the skin, but if it is 
done at the proper time, with water at the right temperature, 
it strengthens and invigorates the whole body. The kind 
of bathing should be determined somewhat by the state of 



HYGIENE OF SKIN AND ORGANS OF SPECIAL SENSE. 115 

the weather, the age, health, and occupation of the indi- 
vidual. 

Why are cosmetics and hair-dyes objectionable? 

The use of cosmetics for the complexion is a frequent 
source of disease, for most of them contain materials highly 
injurious to the skin. Lead is very often used as a coloring 
matter, and is absorbed by the skin, producing ill health by 
lead-poisoning. Most hair-dyes contain lead, and are objec- 
tionable for that reason. They also injure the vitality of 
the hair, and seldom improve its appearance. 

What action has the use of alcohol upon the skin ? 

Alcohol, taken in beverages of any kind, causes more 
blood to flow to the skin. This is shown by the flushed 
face of the man who has been "drinking." If the drinking 
is excessive and long continued, the redness becomes perma- 
nent. This congestion interferes with the proper nourish- 
ment of the skin, and the epidermis collects in spots, giving 
the face the blotchy and degraded look peculiar to the 
chronic hard-drinker. 

What are corns ? 

Corns are thickened portions of the cuticle or epidermis, 
caused by pressure or friction. They are usually found on 
the feet, the result of tight or ill-fitting shoes. They are 
painful because the hardened cuticle irritates the sensitive 
cutis below. The extent of the suffering which they inflict 
upon humanity is a strong warning against tight shoes. 

Mention some ways in which deafness is caused. 

Deafness may be caused in several w r ays : by disease of the 
auditory nerve, the labyrinth, or the tympanum ; by the 
stoppage of the auditory canal by wax or some foreign sub- 
stance ; by a blow upon the ear, or by the concussion pro- 
duced by an explosion, or by the firing of a cannon near by ; 



116 BRIEF LESSONS ON THE HUMAN BODY. 

by a cold which settles in the throat and causes inflammation 
and swelling of the membrane which lines the Eustachian 
tube, or of other parts connected with the middle or inter- 
nal ear. If the cause is disease of the auditory nerve or of 
the internal ear, the deafness may be incurable ; otherwise 
medical aid, patience, and care will usually effect a cure. 

Mention some things to be observed in the care of the eyes. 

The eye is a very delicate organ, and great care should 
be taken to keep it in as perfect a condition as possible. 
The eyes should never be strained by trying to read or sew 
with an imperfect light. They should not be fatigued by 
reading newspapers or other fine print, while riding in a 
carriage, street-car, or railway-train. It is injurious to look 
or gaze at objects which are intensely bright, — at the sun, 
an electric light, a full gas-jet, etc. Books printed in too 
small type should be avoided. It is not well to read while 
lying in bed or on a sofa, as some of the muscles of the eye 
are strained by so doing. 

What should be done if the eyes are near-sighted, or far- 
sighted ? 

In case of near-sightedness or far-sightedness, an oculist 
should be consulted, and the defect, as far as possible, should 
be remedied by using proper glasses. In a case of near- 
sightedness the rays of light come to a focus in front of the 
retina. In a case of far-sightedness they come to a focus 
behind the retina. A near-sighted person should wear con- 
cave glasses, and a far-sighted person should wear convex 
glasses. 

NOTES AND SUGGESTIONS. 

Note 1. To Examine the Structure of the Eye. — The structure of the 
eye can be readily examined by dissecting the frozen eye of an ox. It 
can be sawed from the skull together with a portion of the bone around 



NOTES AND SUGGESTIONS. 117 

it, and then frozen by placing it in salt and ice in summer, and in the 
snow over night in winter. 

2. The Muscular Sense. — We are said to possess five senses, but there 
is another, commonly called the muscular sense. By this sense we are 
able to judge of the weight of different bodies by the muscular effort 
required to lift them. 

3. Senses of Animals.— The senses of many animals are more acute 
than those of man. Some birds surpass in sight, the dog has a keener 
sense of smell, the deer or the rabbit a quicker ear, and the bat is more 
sensitive to touch. 

4. Color-Blindness.— Some persons are unable to distinguish between 
certain colors. This defect is sometimes caused by sickness, but usu- 
ally exists at birth. It is a matter of considerable practical importance 
to persons who work on railroads and boats where colored signals are 
used. Women are seldom color-blind. 



CHAPTER XXIV. 

STIMULANTS AND NAKCOTICS. 

What is a poison ? 

A poison is any substance whose natural effect, when 
applied externally, or when taken into the stomach or blood, 
is to produce disease or death. 

Into ivhat two classes are poisons generally divided? 
Define each. 

Poisons are generally divided into two classes, irritant 
poisons and narcotic poisons. An irritant poison is a poison 
which irritates, or inflames, the organs of the body with 
which it comes in contact. A narcotic poison is one which 
produces sleep, stupor, or paralysis of the nervous system. 
Some poisons are both irritant and narcotic in their effects. 

Name some irritant poisons. 

Arsenic, corrosive sublimate, strong acids, potash, lunar 
caustic, phosphorus, poison ivy, sugar of lead, etc., are 
irritant poisons. 

Name some narcotic poisons. 

Laudanum, morphine, chloroform, belladonna, aconite, 
alcohol, and tobacco are narcotic poisons. 

Among those substances which may be said to be both 
irritant and narcotic in their effects are pink-root, ergot, 
lobelia, etc. 

What is meant iy a stimulant ? 

The word stimulant means that which excites, or goads 






STIMULANTS AND NARCOTICS. 119 

on. Hence a stimulant is any substance which excites some 
organ of the body to greater activity without affording it 
proportionate nourishment. Some poisons are both stimu- 
lants and narcotics in their action ; but just where the stim- 
ulant action ends, and the narcotic action begins, is not 
easy to determine. Opium, alcohol, hasheesh, and tobacco 
are substances of this kind. 

What is opium ? 

Opium is the thickened juice of the poppy-plant, which 
is largely grown in India. The active principle in opium 
is morphine, which gives the sleep-producing property to 
laudanum, " soothing syrups/' paregoric, Dover's powders, 
etc. Taken in too large doses it produces a sleep from 
which there is no waking. Laudanum is made by dissolving- 
opium in alcohol. 

What are the effects of opium ? 

Properly used, opium is one of the most valuable drugs 
at the disposal of the physician ; improperly used, it becomes 
one of the most harmful. The first effect of opium is stim- 
ulating, but the external effects are not as noticeable as are 
those from the use of alcohol. It is generally first used for 
the purpose of obtaining relief from pain, but the sense of 
relief is often so enchanting that the sufferer is unable to 
resist the temptation to repeat its use. In this way the 
opium habit, so called, is formed. This habit, if once estab- 
lished, is almost irresistible, and, if continued, is sure to 
prove fatal. Most physicians now realize the danger, and 
prescribe opium with great caution. It should never be 
taken, or given to others, except on the order of a physician, 
and then exactly as ordered. Many a child has been killed 
by the use of paregoric, " soothing syrups," and the like, 
given by ignorant parents or careless nurses. 



120 BRIEF LESSONS ON THE HUMAN" BODY. 

What diseased conditions result from the continued use of 
opium ? 

The continued frequent use of opium causes a diseased 
condition of the stomach and other digestive organs. The 
opium-eater is therefore a lean, yellow, sallow person. It 
also impairs the muscular and mental powers, especially 
weakening the will. While the intoxication produced by 
opium is of the most exquisite bind, the after effects are 
proportionately horrible. The habit can be broken only 
with intense suffering on the part of its victim. 

What other drugs are similar to opium in their useful- 
ness and in their liability to do harm ? 

Chloral, chloroform, ether, and cocaine are similar to 
opium in their action upon the nerves and brain in diminish- 
ing sensibility to pain and in producing sleep. In the hands 
of careful physicians and skilful surgeons they have proved 
to be great blessings to suffering humanity ; but used with- 
out proper medical advice, they are dangerous agents, — no 
longer remedies, but poisons. Like opium, they are seduc- 
tive in their nature, and their use frequently leads to a habit 
so strong that few possess the will-power sufficient to throw 
it off. 

What is alcohol ? 

Alcohol is a clear, water-like liquid, possessing a hot, bit- 
ing taste, obtained by distilling fermented vegetable juices. 
It exists in all fermented liquors to a greater or less extent. 
Distillation does not make the alcohol, it is only a process 
by which the alcohol is separated from the rest of the liquid. 
It is alcohol which gives the intoxicating property to brandy, 
whiskey, gin, rum, etc. Alcohol, it is said, was first dis- 
tilled from wine by an Arabian chemist about the year 1000 
a. d. The word "alcohol" is of Arabic derivation. 

What is fermentation^ 



STIMULANTS AND NARCOTICS. 121 

If the juices of ripe fruits of any kind, as of apples or 
grapes, are allowed to stand in a warm place for a time, 
they begin to " work," or ferment. New cider, for instance, 
has a sweet taste, but when it begins to ferment, little bub- 
bles of gas appear ; it loses its sweetness, and takes a sharp, 
biting taste. The sugar in the cider has changed into two 
other substances, the gas (carbonic acid) and alcohol. The 
formation of the gas causes the bubbling and sparkling ; the 
alcohol gives the pungent taste. Liquids containing starch, 
obtained by soaking rye, corn, barley, and other grains, can 
be made to undergo fermentation in nearly the same way. 
The starchy matter changes into sugar, and the sugar into 
carbonic acid and alcohol. Fermentation then is the change 
of organic substances by which their starch, sugar, etc., are 
decomposed, under the influence of water, air, and warmth, 
and their elements recombined into new compounds. 

What is distillation ? 

Distillation is the changing of a liquid into a vapor by the 
application of heat, and then condensing the vapor into a 
liquid again by cooling it. Some liquids boil, or change to 
vapor, at lower temperatures than others ; and this fact is 
made use of in order to separate one liquid from another by 
distillation, as alcohol from water. Alcohol becomes vapor 
when heated to 173° F., water when heated to 212° F. 

How are alcoholic liquors obtained ? 

Alcohol is produced in only one way, by the fermentation 
of some liquid containing sugar or starch. All the so- 
called alcoholic liquors, brandy, rum, gin, pure alcohol, 
etc., are separated from these fermented liquids by distil- 
lation. The fermented liquid is heated to a temperature 
sufficient to change the alcohol into vapor. This vapor is 
collected in a cool receiver and condensed. The result is a 
new liquid containing a much larger per cent, of alcohol. 



122 BRIEF LESSONS ON THE HUMAN BODY. 

It is not pure alcohol, because some steam and fragrant 
vegetable substances pass into the cool receiver along with 
the alcoholic vapor. The taste, or flavor, of the distilled 
liquor will vary just as the taste of the fruit or vegetable 
from which the fermented liquid is obtained varies. It is in 
this way that each kind of liquor obtains its characteristic 
flavor and odor. 

Brandy is distilled from the fermented juice of grapes, 
or wine ; rum is obtained in the same way from fer- 
mented molasses ; gin from fermented barley and rye, and 
afterwards flavored with juniper berries ; whiskey from 
fermented corn, rye, barley, or potatoes ; the alcohol of 
commerce is obtained by re-distilling whiskey. These dis- 
tilled liquors contain from forty to fifty per cent, of alcohol ; 
the rest is water flavored according to the vegetable sub- 
stance used in their manufacture. 

Beer, wine, and cider are not distilled liquors, and contain 
a much smaller amount of alcohol. 

Mention some good uses to tvliich alcohol may be put. 

Alcohol has many valuable uses in medicine and the arts. 
Many medicines are prepared by mixing drugs with it. It 
is used for dissolving gums and resins used in paints and 
varnishes. Perfumes and extracts for flavoring, etc., are 
made by combining it with various oils and essences. It is 
useful as a burning-fluid where great heat and little light 
are desired. As it will not freeze, it is used in making 
thermometers. It absorbs the water, and so prevents the 
decay of substances put into it ; it is therefore useful for 
preserving the bodies of small animals, insects, and other 
specimens for museums, etc. Many others might be men- 
tioned, but these are sufficient to show that alcohol, rightly 
used, is a valuable servant. 



CHAPTER XXV. 

STIMULANTS AND NARCOTICS. — CONTINUED. 

Is alcohol a food? 

Alcohol is composed of carbon, oxygen, and hydrogen 
only. It does not contain nitrogen, therefore it lacks one 
important element, and it will not make muscle. It con- 
tains no iron for the blood, and no phosphorus or lime for 
the bones. It leads to the overgrowth of some tissues, as 
connective tissue and fat ; but it does not develop bone, 
muscle, or brain. It does not satisfy hunger except by dull- 
ing the sensibility of the nerves of the stomach. A true 
food becomes a part of the tissues of the body, but alcohol 
appears to remain in the body unchanged, until it is cast 
out in vapor from the lungs, pores of the skin, and by the 
kidneys. The conclusion is that alcohol is not a true food. 

Does alcohol help to keep up the ivarmth of the body ? 

Many people take alcoholic drinks under the impression 
that they afford warmth, but the increased bodily tempera- 
ture which they produce is only temporary and is due mainly 
to the stimulating effects of the alcohol upon the circulation. 
This slight increase, however, is more apparent than real ; 
because, in fact, the stimulated circulation has brought 
more blood to the surface, and so increased the heat of the 
surface at the expense of the inner portions of the body. 
This surface heat is rapidly lost by radiation, so that in the 
end the effect has been to diminish the warmth of the body, 



124 BRIEF LESSONS ON THE HUMAN BODY. 

instead of increasing it. Tests made by army officers, Arctic 
explorers, and others who have given special study to the 
question, go to prove that the use of alcohol lessens the 
power to endure extremes of heat or cold. 

Is the moderate use of alcoholic drinks safe or beneficial? 

In almost every instance the moderate use of alcoholic 
drinks, as in beer-drinking, etc., is one of the stages which 
brings the drinker to their immoderate use in stronger 
forms and in increased quantities. An eminent physician 
says that it is a physiological fact that the attraction of 
alcohol for itself is cumulative ; that so long as it is present 
in the human body, even in small quantities, the longing 
for it, the sense of requirement for it, is present ; and that, 
as the amount of it insidiously increases, so does the desire. 
There is an abundance of emphatic testimony which goes 
to prove that the use of alcohol, to an extent far short of 
what is necessary to produce intoxication, injures the body 
and diminishes mental power. The drinker himself may 
not be conscious of these effects, but those who know him 
best can see that it takes something from the fineness of his 
character, interferes with the keenness of his judgment and 
the evenness of his temper. Absolute security is found 
only in total abstinence. 

Is the taste for alcohol inherited? 

In answer to this question Dr. Willard Parker of New 
York says : " There is a marked tendency in nature to trans- 
mit all diseased conditions. Thus, the children of con- 
sumptive parents are apt to be consumptive. But, of all 
agents, alcohol is the most potent in establishing a heredity 
that exhibits itself in the destruction of body and mind. 
There is not only a propensity transmitted, but an actual 
disease of the nervous system." 



STIMULANTS AND NARCOTICS. — CONTINUED. 125 

Dr. Albert Day says : " Were it now possible to deprive 
every man, woman, and child of intoxicants in the future, 
I believe it would require a century to eliminate by the nat- 
ural laws of evolution the disease produced in the past, by 
alcoholic indulgence." Beyond a doubt the effects of alco- 
hol are transmitted from parent to child, from generation to 
generation, in a tendency to nervous diseases, mental weak- 
ness, imbecility, and insanity. 

Does alcohol cause a tendency to disease ? 

There is the best of medical authority for saying that alco- 
hol alters and impairs tissues so that they are more prone 
to disease. It causes an increased liability to fevers and in- 
flammations. Yellow fever is more apt to be fatal when it 
attacks those who use liquors freely; the same thing is true 
with persons who have pneumonia, or inflammation of the 
lungs. Life-insurance tables show that a temperate man 
stands a better chance of a long life than an intemperate 
man. According to such tables, at the age of twenty, the 
temperate man has a chance of living 44.2 years ; at the age 
of thirty his chance is 36.5 years : at forty it is 28.8 years. 
At the age of twenty the intemperate man's chances are 
15.6 years ; at thirty, 13.8 years ; at forty, 11.6 years. This 
is a gain of twenty years or more in favor of the temperate 
man. 

Does alcohol weaken the moral character? 

One of the first effects to be noticed, after indulgence 
in alcoholic drinks, is the lack of self-control. The half- 
drunken man is pleased or enraged without sufficient cause ; 
he says and does rash things, his logic is muddled, he is un- 
able to appreciate nice shades of right and wrong, and with 
this general mental weakness comes a dulness of the moral 
sense. The newspapers abound in accounts of thefts, as- 



126 BRIEF LESSONS ON THE HUMAN BODY. 

saults, riots, and murders, committed by persons under the 
influence of intoxicating liquors, and prisons are full of 
men undergoing punishment for crimes committed under 
such circumstances. 

Describe the stages of intoxication by alcohol. 

The effects of alcohol upon the nervous system may, ac- 
cording to Dr. Eichardson, be divided into four successive 
stages, as follows : first, the stage of excitement ; second, 
the stage of muscular weakness ; third, the stage of mental 
weakness ; fourth, the stage of unconsciousness. 

In the first stage, the nerves which lead to the capillaries 
and small blood-vessels become partially paralyzed, so that 
they are unable to regulate the flow of blood. The restraint 
being taken away, the heart beats faster, and the blood 
rushes through the system with increased force. The first 
effect is usually a feeling of animation and good nature. 
The increased flow of blood stimulates the brain and mus- 
cles to greater activity, but it confers no permanent power 
to either. The extra work which a man is able to do under 
such circumstances is only temporary, and will be followed 
by a corresponding weakness ; if talk or conversation has 
been brilliant, it has been made so at the expense of the 
judgment and understanding. 

As the influence of the alcohol advances to the second 
stage, it begins to produce its narcotic effects. The spinal 
cord is affected, and the drinker loses control of some of his 
muscles. The muscles of the legs, lower lip, and eyelids 
seem to fail first. This appears in the unsteady gait and 
in the leering, expressionless look of the drunkard, caused 
by a lack of tension of the muscles about the mouth and 
eyes. 

In the third stage, or stage of mental weakness, the stimu- 



STIMULANTS AND NARCOTICS. — CONTINUED. 127 

la ting effect has begun to pass off. The memory has begun 
to fail, the will and the judgment are impaired, and all the 
powers of the mind are in confusion. The tongue is loos- 
ened, and self-control nearly or altogether lost. The lower, 
or the animal nature, takes control of the man, and educa- 
tion, self-respect, and social restraints have lost their power 
over him. He is quick to take offence at real or fancied 
affronts, and is liable to commit crimes and do deeds of vio- 
lence at the slightest provocation. 

The fourth stage is the stage of stupor, or unconscious- 
ness. The narcotic properties of the alcohol have com- 
pleted their work, and, in common speech, the man is " dead 
drunk/ 7 motionless and insensible. And were it not for the 
fact that the nerve-centres which control the action of the 
heart and organs of breathing are the last to be affected, 
every case of complete intoxication would be a case of 
death. This condition remains for an indefinite number 
of hours, when gradually the mind rallies from the stupor. 
For several days there is a distressing weariness of nerves 
and muscles, which shows how powerful were the effects of 
the alcohol, and with what difficulty the injured organs re- 
cover their normal condition. And it is doubtful whether 
a brain once thoroughly intoxicated ever fully recovers from 
the effects. 

What is the nature of delirium tremens'? 

Delirium tremens is a nervous disease due to the excessive 
use of alcohol. It is a frightful form of temporary insanity. 
It may be caused by a single fit of intoxication, but it is 
usually the result of an excessive and long-continued use of 
intoxicating liquors. The victim is nervous and restless ; he 
sees spectres, usually foul and horrible, about him ; he im- 
agines that he is surrounded by snakes and frightful mon- 



128 BRIEF LESSORS ON THE HUMAN BODY. 

sters, from which he tries to escape. The delirium may 
continue until the victim dies from exhaustion, or until he 
sinks into a stupor, from which he may awaken compara- 
tively sensible ; but unless the strength of the victim has 
been greatly reduced by the use of alcohol, delirium tre- 
mens is not usually fatal. 



